BNUS ANNUAL REPORT-2016

BANGLADESH
NETWORK OFFICE FORURBAN SAFETY
BUET, DHAKA, BANGLADESH
Edited By:

Mehedi Ahmed Ansary

April 20171

CONTENTS
PART-I: CYCLONE ROANU, 21 MAY 2016
3
PART-II: FIRE FROM ELEVATOR CRASH IN AT ALAUDDIN17
MARKET IN UTTARA OF DHAKA, 24 JUNE 2016
PART-III: FIRE IN INCIDENT IN TAMPACO FOILS LTD AT BSCIC
INDUSTRIAL AREA, TONGI, GAZIPUR ON 10 SEPTEMBER, 2016
20
PART-IV: MEASUREMENT OF ELECTRICAL RESISTIVITY WITHIN A
POWER PLANT AREA
26
PART-V: ASSESSMENT OF UNDERLYING CAUSES OF FIRE RISKIN OLD DHAKA: A CASE STUDY OF ISLAMBAG AREA IN WARD
NO. 65, DHAKA SOUTH CITY CORPORATION
36
PART-VI: SEISMIC MICROZONATION OF COX'S BAZAR MUNICIPAL
AREA BANGLADESH
50
PART-VII: EARTHQUAKE RELATED RESEARCH AND ACTIVITIESIN BANGLADESH DURING THE LAST SIX YEARS (2010-2016)
64
PART-VIII: USE OF JET GROUTING IN RETROFITTING OF A RMG
79
FACTORY BUILDING IN CHITTAGONG, BANGLADESH
PART-IX: AMBIENT VIBRATION ANALYSIS OF HERITAGE
UNREINFORCED MASONRY BUILDINGS IN BANGLADESH
92
PART-X: EFFECTS OF RELATIVE DENSITY AND EFFECTIVE
108
CONFINING PRESSURE ON LIQUEFACTION RESISTANCE OF SANDS
PART-XI: EVALUATION OF LIQUEFACTION POTENTIAL FROM SPT
AND CPT: A COMPARATIVE ANALYSIS
117
PART-XII: CPT-SPT BASED CORRELATIONS FOR COHESIONLESS SOIL
FOR UTTARA 3RD PHASE, DHAKA
125
PART-XIII: THE UTILIZATION OF CPT AND SPT TO OBTAIN SOIL
PARAMETERS FOR C- ɸ SOIL AT UTTARA 3RD PHASE, DHAKA,BANGLADES
155
PART-XIII: EARTHQUAKE IN TRIPURA, 3 JANUARY 20171992

PART-ICYCLONE ROANU, 21 MAY 2016
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed Ansary31. Introduction
The naming of tropical cyclones is a recent phenomenon. The process of naming cyclones involves
several countries in the region and is done under the aegis of the World Meteorological Organisation.
According to Hurricane Research Division, tropical cyclones are named to provide ease ofcommunication between forecasters and the general public regarding forecasts, watches, andwarnings. Since the storms can often last a week or longer and that more than one can be occurringin the same basin at the same time, names can reduce the confusion about what storm is being
described. Eight countries in the region - Bangladesh, India, Maldives, Myanmar, Oman, Pakistan,
Sri Lanka and Thailand - all contributed a set of names which are assigned sequentially whenever a
cyclonic storm develops over the Arabian Sea and Bay of Bengal. Every time a cyclone occurs, aname is picked in the order of the names submitted by these countries. The cyclonic storm Roanu has
been named by Maldives which means “coir rope” in Maldivian (Dhivehi) (Daily Star, 21 May
2016).

Figure 1: Projected track of cyclone Roanu
2. Meteorological History
Under the influence of a trough, a low pressure area formed over the Bay of Bengal on 14 May. It
slowly consolidated as it paralleled the east coast of Sri Lanka, prompting the India Meteorological
Department (IMD) to classify it as a depression on 17 May. On 19 May, the IMD reported that thestorm had reached cyclonic storm intensity, and assigned it the name Roanu. In the late hours of thatday, Roanu showed a weakening trend after most of the convection covering the LLCC was sheared4off. Roanu re-intensified as it accelerated east-northeastwards towards the coast of Bangladesh, andreached its peak intensity with winds of 85 km/h (50 mph) (Dhaka Tribune, 19 May 2016). On 21
May, around 1pm local time, Tropical Cyclone Roanu made landfall along the Barisal-KhulnaChittagong coastal region of Bangladesh, bringing heavy rain, winds of up to 88km/h, and storm
surges of up to 2m. While crossing the coastline, the storm had a speed of 60-80 kilometre per hourwhile heading east-northeastwards. It took 4-5 hours to cross the coast (Daily Star, 21 May 2016;
Daily Sun, 21 May 2016). Some areas, including the offshore islands and chars, experienced tidal
surges 4 to 5 feet above the normal tide. Continuing to accelerate inland, Roanu steadily weakened
and degenerated into a remnant low the next day. As of 22 May, Cyclone Roanu had moved on to
Myanmar (Dhaka Tribune, 22 May 2016).
3. Preparedness and Response
On May 19 Bangladesh Meteorological Department advised maritime ports of Chittagong, Cox’s
Bazar, Mongla and Payra to hoist local warning signal No. 4. All fishing boats and trawlers along thenorthern part of the Bay and deep sea were asked to stay close to the coast and move with caution
until further notice. Vessels were also advised not to venture into deep sea. In the evening after the
deep depression transformed into a cyclonic storm, the Disaster Ministry held a special preparatory
meeting with concern authorities for taking precautionary steps ahead of the Cyclone Roanu. Afterthat the government started to prepare for a massive evacuation in 18 coastal districts Bangladesh.
All the cyclone shelters in these districts were kept ready. District administrations in coastlines werealso asked to mobilize nearly 60,000 volunteers trained under the Cyclone Preparedness Programme(CPP) and chart out detailed plans to face the impending disaster by holding emergency coordination
meetings. The weekend holidays of civil servants of the 18 districts were cancelled as well.
Preparations were underway to keep the damage to a minimum, and volunteers and officials weresent out with megaphones to issue alerts.
On May 20 with cyclone Roanu approaching closer, Chittagong port and coastal districts ofChittagong, Noakhali, Laxmipur, Feni, Chandpur, and their offshore islands and chars were put
under danger signal number 7, Cox’s Bazar port and coastal district of Cox’s Bazar and its offshoreislands and chars have been put under danger signal number 6, and Mongla and Payra ports andcoastal districts of Bhola, Borguna, Patuakhali, Barisal, Pirozpur, Jhalokathi, Bagherhat, Khulna,
Satkhira have been put under danger signal number 7. Since 5.10 pm on May 20, authorities
suspended water transport through the country until further notice. Alongside, the government
scrapped all leaves and holidays of officials and staff of Roads and Highways Department in the
country’s coastal areas as part of its preparation for the cyclone. All staff and officials were asked to5remain alert to keep uninterrupted road communication in the coastal areas. BMD was issuing
regular special weather bulletins on the storm. Department of Disaster Management directed all thecoastal district authorities to evacuate people from their homes and send them to cyclone shelters.
Volunteers launched campaigns in the coastal areas to alert people to evacuate to safe zones andcyclone shelters that have been prepared. The government’s Cyclone Preparedness Programme andBangladesh Red Crescent Society were directing the evacuation process.

(a) Water transports harbored at the banks of(b) Fishermen shelving their boats in

Karnaphuli River in Chittagong on May 20

Firingibazar area of Karnaphuli river in2016

Chittagong on May 20, 2016
Figure 2: Restriction on water transport

In Chittagong, control rooms were set up in coastal areas to facilitate evacuation of the marginalized
people to safety shelters. The district administration set up control rooms in every upazila to monitor
overall situation. A hotline - was opened to keep people in touch with updates in the district. All
cyclone shelters in the coastal districts were kept open to people. Awareness campaign was started
through loud speakers since afternoon and the relief workers were ready to combat any situation.
Following a meeting of the Chittagong Port Authority, it asked all mother vessels to go to safer
places and lighter vessels to move upstream. It stopped activities in the outer anchorage. At around
7:30pm on that day, the port authority ordered 19 vassals anchored in the port to depart jetty before
the storm struck. In Cox’s Bazar, the members of army, Border Guard Bangladesh, police and civil
surgeon were deployed at different strategic points in the district as safety measures. Control room
was set up to oversee the overall situation in the district. Around 516 cyclone shelters withaccommodation capacity of around 5.15 lakh people were kept prepared including adequate amountof dry foods to ensure relief work.
The coastal districts of Chittagong, Noakhali, Laxmipur, Feni, Chandpur, Bhola, Borguna,
Patuakhali, Barisal, Pirojpur, Jhalakati, Bagherhat, Khulna, Satkhira and their offshore islands andchars remained under the danger signal number seven on May 21. The Shah Amanat International
6

Airport, Chittagong suspended all of its flight operations due to Cyclonic storm Roanu. Meanwhile,
goods loading and unloading from all ships remained suspended by Bangladesh Inland Water
Transport Authority at Chittagong seaport since the morning as Cyclone Roanu nears the BarisalChittagong coast. In Chittagong, issues were ordered to ensure power supply, sanitation, medical
assistance and enough dry food at the shelters. There were around 2,500 shelters in the cycloneprone areas and 55,000 volunteers at work. Each shelter can hold around 1,500 people. The
authorities were using megaphones in coastal areas to urge people to move to the shelters.
Apprehending mudslides, the Chittagong district administration also asked people living in thefoothills to move out.

Figure 3: A ship got stranded at Patenga sea
beach during the cyclone Roanu

Figure 4: Sea water overflowing beri badh at
Patenga sea beach, Chittagong as Cyclone
Roanu made landfall

As part of addressing the risk of cyclone Roanu, eight community radio stations in the coastal regionof Bangladesh broadcasted programmes for 348 hours for three days continuously from 19 May
2016. The community radio stations broadcasted their programmes round the clock to keep
communities alert during and after the cyclone Roanu that hit country’s coastal belt on 21 May 2016.
A total of 116 community broadcasters --female 37, male 79 -- volunteers and members from 175
listeners clubs worked throughout the whole service. As the storm weakened, the cautionary signal
was lowered to 3 at all the Maritime ports but goods handling remains suspended at Chittagong port
after the cyclone landfall on May 21.
More than 538,000 people were moved into 3,554 temporary cyclone shelters. Despite suchpreparedness at the cyclone shelters in Sitakunda upazilla under Chittagong district, most of the
shelters remained vacant as locals termed Roanu a usual natural phenomenon. Three shelters in theupazila were completely vacant on May 21 as people paid no heed to the repeated warnings of local
Red Crescent volunteers. They saw such disasters many times in the past. Besides, cyclone shelters
can ensure accommodation only for them but not for their domestic animals. These animals are partof their life and they just cannot leave them in a situation where they might die or get injured.
7

(a) Villagers going to cyclone shelter(b) Cyclone shelter at Mirapara Cyclone Shelter
in Patenga, Chittagong

Figure 5: Cyclone shelter
4. Impact of the Cyclone
4.1 Secondary hazards
Under the influence of the cyclonic storm, heavy Rain and thunder showers accompanied bytemporary gusty and squally wind was continuing at most places over Dhaka, Khulna, Barisal,
Chittagong and Sylhet divisions and at many places over Rajshahi and Rangpur divisions since earlymorning on May 21. Rains, caused by cyclone 'Roanu', swamped many parts of the capital, leaving
the city life in disarray. Most of the low-lying areas in the city also went under rainwater. Roads in
Kakrail, Mouchak, Malibagh, Mirpur, Kazipara, Shewrapara, Motijheel, Shantinagar, Razarbagh,
Arambagh, Merul Badda, Elephant Road, Dhanmondi and Paltan areas were submerged, as the city's
clogged drains failed to absorb the rainwater.

(a) Heavy rainfall in Dhaka(b) Water logging due to heavy rainfall

Figure 6: Heavy rainfall resulted due to Cyclone Roanu
Commuters experienced immense sufferings for lack of transports, and many of them had to wadethrough the water-logged streets. They complained that rickshaws and CNG-run auto-rickshaw
drivers charged them excessive fares, taking advantage of the inclement weather. The BMD,
8

meanwhile, recorded 43 mm of rain in 24 hours till 9:00am on May 21. Meanwhile, most of the lowlying areas of the district, including Chittagong, Noakhali, Lakshmipur, Feni, Chandpur, Bhola,
Barguna, Patuakhali, Barisal, Pirojpur, Jhalakati, Bagerhat, Khulna and Satkhira, were inundated by
the tidal surge. Banshkhali upazila in Chittagong is among the worst affected areas as several unions
remained inundated with seawater rushing into the storm-battered villages till May 23.
4.2 Human Casualty
The cyclone caused at least 26 deaths and 100 injuries in seven districts across the country. Amongthem 12 were in Chittagong, 3 each in Noakhali, Cox's Bazar, and Bhola; 1 each in Feni, Patuakhali
and Lakshmipur. Most of them died due to houses or trees collapsing on them in the storm or bywaves sweeping them away. At least 20 people were admitted to Chittagong Medical College
Hospital alone. At least 41 people were injured as Roanu uprooted trees and flattened homes in Cox's
Bazar's Moheshkhali, Kutubdia and Ramu upazilas. At least forty people are also missing in theseareas. In Feni, four people were reported missing. In Bhola, a cargo vessel with four crew members
went missing in the Meghna. Around 4.83 lakh people in 104 unions of different upazilas in
Chittagong were affected by the cyclone. Some 103,000 families were affected by it, of them, around
19,437 were affected severely and 83,660 partially. Around 50 thousand people in Cox’s Bazar havebeen affected in the cyclone. Over 80 villages in Patuakhali and Barguna were flooded as a dam
broke forcing people to move out.

Figure 7: Village in Banshkhali faded away due to cyclone Roanu
4.3 Impact on Shelter
Around one lakh houses were damaged and about 150,000 families were affected by the cyclone in
the three districts. According to primary estimate of the district administration in Chittagong, around
2.5 lakh houses were damaged in the cyclone. In Cox's Bazar, at least 29,000 houses were damaged
and 22,128 families were affected in the 71 unions of eight upazilas. In Bhola, several hundredhouses were damaged by the storm as cyclone Roanu was getting closer to the coastal areas of
Bangladesh. Over 100 houses were damaged in Patuakhali.
9Figure 8: Impact on Shelters: Damages homes in Tajumuddin upazila of Bhola
4.4 Impact on Agriculture
In Chittagong Division, seedbeds of aush paddy on around 400 hectares of land were under water.
The cyclone ruined crops on 154 acres of land completely and that on 2,541 acres of land partially in
Chittagong. Besides, 360 betel leaf orchards and vegetables on 3,100 hectares of land were damagedby the storm, according to the Department of Agricultural Extension (DAE). According to primaryestimate of the district administration in Chittagong, the cyclone washed away domestic animals ofsome Tk 100 crore, and cropland worth around Tk 50 crore were damaged in the cyclone. At least
15,000 cattle were washed away in Sandwip alone. The storm dealt a heavy blow to shrimp farming
as a tidal surge ravaged 2,117 shrimp enclosures in seven upazilas, causing a loss of around Tk 13
crore in Cox’s Bazar. Over 2,000 livestock and 40,000 ducks and hens were swept away and 500
acres of grain field were ruined in the cyclone in Kutubdia of Cox's Bazar. Financially, the total
damages would amount to about Tk 200 crore. Fish worth several lakh taka were washed away in
Bhola. In Patuakhali, the farmers of all eight upazilas have to count losses as their standing crops
were flooded by tidal surge and heavy rainfall. Besides, crops on 3,451 hectares of land were badly
damaged in the eight upazilas, according to Patuakhali Agriculture Extension Department.

(a) Damaged local shops in Boubazar area of(b) Devastated shops at Patenga Sea beach,
Rangabali upazila, Patuakhali
Chittagong
Figure 9: Impact on properties10

4.5 Impact on Properties
Damage to properties was extensive. Several hundred shops of Jhinuk Market in Patenga ofChittagong were swept away. Around 75 shops have been destroyed by the tides in the naval area,
informed locals. In Patenga beach area around 300 shops were completely washed away, said
Shamshul Alam, general secretary of Patenga Sea Beach Shop Owners Co-operative Association. In
Chittagong, property and goods worth of more than Taka 100 crore have been damaged in theReazuddin Bazar, Khatun-ganj, Boxirhat, Terrybazar, Chaktai, and Chittagong Shopping Complex
due to cyclonic storm. Around 500 shacks were damaged in Banshkahli. Sea water entered the shops
and warehouses in Khatungaj, Chaktai, Asadganj and Korbaniganj areas in Chittagong city during
the storm. In Kutubdia of Cox's Bazar, about 167 educational and religious institutions were either
fully or partially damaged.

(a) Damaged coastal embankment at(b) Damaged dam at Nalchiraghat of Hatiya,

Banshbari union in Sitakundu upazila

Noakhali(c) Damaged Airport road, Chttagong(d) Damaged road in Kuakata sea beach11

(e) Damaged road in Kutubdia, Cox’s Bazar
Figure 10: Impact on infrastructure
4.6 Impact on Infrastructure
Rain triggered by the cyclone flooded embankments in the three upazilas and damaged many roads,
which will worsen the condition of roads as the rainy season is going to begin soon. A 30-kilometre
stretch of the 130km long embankment in Banshkhali upazila in Chittagong was damaged, while 20
kilometer in Sandwip and 10 kilometer in Anwara. The villagers are now in constant fear that thedamaged part would collapse any moment, allowing seawater to swamp their houses and fields.
Eighteen kilometres of embankment was washed away while 157 kilometres of road link suffereddamage in Kutubdia of Cox’s Bazar. A chill of fear swept over around 20,000 people in Sitakunda’s
Banshbari union as high tidal surges hit the dilapidated embankment in the area. The barrage, which
was built to protect the homes and crops of locals, has fallen into disrepair over the last six years as
the local administration took no measures to renovate the 3km structure. They said they had
apprehensions that the embankment might collapse anytime after tidal surges lashed it.
Along with damaging Naval Academy road, cyclone Roanu has inflicted massive damage on the
Chittagong city protection embankment. The four-kilometer naval road facilitates movement fromairport. It's a famous tourist destination for its location along the estuary of Karnaphuli River and the
Bay of Bengal. It is owned by Chittagong Port Authority. The mayor had already informed them andthey said they would start repairing soon. People living in the coastal areas of Patenga and South
Halishahar are in fear whether it will be able to stand the high tide during the rainy season when thesea condition will be rough. If the embankment could not stand the tidal surge, then around three12

lakh people would suffer. Moreover if the trees had not been cut down, it would not have happened.
They were cut a few months ago for implementing the Outer Ring Road project. Some CDA officials
were seen repairing the most damaged parts of the embankment by filling sand around 12:00 noon on
May 23.
Cyclone Roanu has done so much damage to the Kuakata beach that it is difficult to even take a walkon it now. A portion of a connecting road from zero point to the beach was washed away as tidal
surges hit the beach on Saturday. Rubble of structures, roads and stumps of uprooted trees laidscattered along the beach from Lembur Char to Gangamoti. Trees of the coconut garden, Tamarisk
garden and Gangamoti reserve forest were badly damaged in the cyclone. The storm also destroyed
over 25 temporary shops.
4.7 Impact on Power Supply and Telecommunication
Power supply was cut in all seven upazilas of Patuakhali since May 20. There were power cuts in
Barisal and in Pirojpur. The power distribution system was seriously disrupted on May 21. So thepower supply was suspended immediately after the cyclonic Roanu hit the Barisal-Chittagong coastnear Chittagong at noon. The cyclone disrupted telecom services in the coastal areas, particularly
cellular services, as many of the transmission centers of mobile operators were down due to a powercrisis. However, many subscribers got back services by May 23 evening. Operators also took
preparatory measures to minimize the expected disruption before the storm hit. Subscribers ofChittagong area were severely affected by Roanu while those from Noakhali and a greater part ofComilla region also suffered. Some parts of Barisal, Bhola and Cox's Bazar were also affected, andcellular services of all operators suffered due to power cuts.

Figure 11: People trying to salvage belongings from their ruined houses at Premashia in Banshkhali
upazila of Chittagong
134.7 Impact on Human Life
Upon their return home from cyclone shelters, many found their houses razed to the ground,
belongings gone, crops ruined and fish farms washed away. The affected people were passing theirdays without food and pure drinking water since May 21, after losing everything to the cyclone.
According to Chittagong District Relief and Rehabilitation Office (DRRO) homeless people of thetwo upazilas were living at the cyclone shelters as it is too tough for them to rebuild houses
immediately. In Bhola, around 10,000 people of Tazumuddin Upazila were running short of foodafter the cyclone destroyed their homes. Even 48 hours after the cyclone, many people in the stormhit villages complained of getting no aid from the government. Around 500 students including 50
examinees of the ongoing Higher Secondary Certificate examination have plunged into a deep crisisas they lost their text books and other school accessories in the cyclone in the Tajumuddin upazila of
Bhola.

Figure 12: Rescue operation in Patenga Sea beach, Chittagong
5. Relief Works
The affected people were in urgent need of relief in terms of rice, oil, salt, sugar, safe water andmedicine to survive until starting life anew. The Disaster Management and Relief Minister visited
Banshkhali and Anwara upazilas on May 23 and assured the affected people of providing with tin
sheets and money for constructing their houses. He gave Tk 20,000 each to the families of 12 victims
in Khankhanbad union of the upazila and ordered the local administration to arrange adequate relief,
food and water for the affected people. As of May 24 the local administration distributed Tk 3.30
lakh, 87 tonnes of rice, 80 sacks of puffed rice and molasses among the cyclone-hit people in the
district.

14

Figure 13: Relief operation by Bangladesh Navy in association with local administration
Bangladesh Navy took the initiatives to hand out relief materials to the victims of cyclone Roanu
when cyclone affected people were put in a severe crisis due to a shortage of food, drinking waterand medicine, the release added. As part of the efforts, around 500 navy personnel along with six
ships and high-speed boats were deployed in the coastal areas to rescue and provide relief to thevictims of the cyclone Roanu. The navy in association with local administration is providing security
and relief to Roanu victims in Kutubdia and Maheshkhali areas. The relief materials include fooditems, hygienic water, saline and medicines have already been taken to the affected areas. Besides,
navy teams are continuing search operations in the deep sea.
6. Lessons Learned
Bangladesh is vulnerable to cyclones because of its location at the triangular shaped head of the Bayof Bengal, the sea-level geography of its coastal area and its high population density. In recent years,
Bangladesh has developed tremendously in the area of disaster management, which is well ahead ofmany countries. This is why the country is considered a role model in managing natural disasters.
The two deadliest cyclones occurred in 1970 and 1991 had claimed some 500,000 and almost
140,000 lives respectively. But during the past 20 years, the country managed to reduce deaths andinjuries from cyclones while the most recent severe cyclone Sidr of 2007 caused an estimated 4234
deaths, a nearly 50-fold reduction compared with the devastating 1970 cyclone. Cyclone Roanu
caused twenty four deaths with 88 kilometres wind speed per hour, while another such tropical tidal
storm Aila of 2009 with identical intensity had claimed 200 lives when it ravaged the coastlines.
Thus, in terms of casualty figures the loss of lives caused by the Roanu was nearly 10 times less thanthat of Aila of 2009. It is a testament to the country’s cyclone response and disaster preparedness
systems that despite its intensity, the storm caused far fewer deaths than many previous cyclones ofthis scale in past decades.
15

The disaster management ministry, fire brigade and meteorological department worked together tokeep the impact of Roanu to a minimum. This included a massive evacuation campaign, mobilisationof medical aid and the readiness of a large number of volunteers as well as cancelation of weekly
holidays of government officials in 18 coastal districts. Apart from prompt alerts to the people,
including fishermen and trawler operators regarding the advancing cyclone, operations of water
vessels were suspended and the airport in Chittagong was closed, for safety reasons. The strengthand attributes of the disaster management strategies include community resilience, volunteerism, the
Early Warning System, community based decision making process, government commitment, avibrant NGO sector and an appreciable legal and institutional framework. Early warnings,
preparedness, proactive measures, and evacuation of certain areas by government, the communities
themselves, and volunteers, illustrated how death and destruction during a natural disaster can be
drastically limited. But the storm has left several thousand people homeless, hungry and utterly
devastated, apart from doing damage to the infrastructure. It is important now to ensure timely relief
and rehabilitation is provided to the many thousands of people who saw houses, crops, and livestock
destroyed in the cyclone so that they can rebuild their homes and their lives.
Lessons must also be learned about how to further improve cyclone preparedness. Roanu also offers
important lessons in recovery compared to previous disasters. Most of the areas hit by the cyclone
were also affected by cyclone Komen, and two floods, in 2015. Arguably, inadequate investment inrecovery after the 2015 disasters, combined with a limited investment in measures to reduce disaster
impacts, including in infrastructure, resulted in Roanu having greater impact in those vulnerable
areas. Once again, inclusion of short and long-term risk in infrastructure development has emerged
as a major priority for a resilient Bangladesh. Emphasis should be given on other infrastructure
improvements as well, such as disaster-resilient roads and bridges, paved trading areas, integrated
water supply systems, efficient power supply systems, and proper drainage and sanitation facilities.
These infrastructure improvements are vital both to prevent loss of life, and to improve people’s
standard of living and make them more resilient to extreme weather events.

16

PART-II

FIRE FROM ELEVATOR CRASH IN AT
ALAUDDIN MARKET IN UTTARA OF DHAKA,
24 JUNE 2016
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed Ansary17

On 24 June 2016, a fire initiated with an explosion at 17-storied Tropical Alauddin Tower Shopping
Complex in Uttara of Dhaka around 6:15pm. The fire originated at one of the three basements of 15storey Tropical Alauddin Tower Shopping Complex after a lift full of passengers fell in its shaft witha loud bang. The fire quickly spread in the mall. After initiation of fire, smoke was seen coming out
from the third, fourth and fifth floors. The explosion ripped apart the market’s basement andshattered the window panes. The fire did not spread to any of the upper floors of the building, whichmostly house shops, but the ceiling of the ground floor came off, damaging shops, doors andwindows. After getting informed, a total of 13 fire fighting units of Fire Service and Civil Defense(FSCD) were deployed to bring the fire under control. The fire was brought under control within one
and half hour.
Over 100 people were injured in the incident including some people with severe burn injuries. Three
victims including 10-year-old girl, an eight-month-old boy and their father were apparently in criticalcondition and were sent to Uttara campus of Bangladesh Medical College Hospital. Later,
considering their critical condition they were transferred and admitted in the burn unit of the Dhaka
Medical College Hospital. On the next day, one of the victims died at Dhaka Medical College
Hospital taking the death toll in the incident to seven. Most of the injured were pedestrians, includingchildren, who sustained wounds as pieces of glass and other fittings fell on them from different
floors.
Meanwhile, the fire service and civil defence formed a four-member probe committee, headed by its
deputy director Zahurul Haque to investigate the incident. After forming the committee, they were
investigating the accidents and restricted public entry to the basements of the building for proper
investigation. Moreover, they had sent letters to Rajuk, Dhaka North City Corporation and
Bangladesh University of Engineering and Technology to investigate the matter and teams of thoseinstitutions had already visited the spot.
From investigation it was found that an elevator snapped and crashed in the basement and started thefire. In primary investigation it was found that the electro-mechanical maintenance of the shopping
mall was poor. So the building, considering the electro-mechanical maintenance, might be calledrisky. This resulted in the crash of the lift and eventually the explosion at the basement initiated thefire. Additionally, under the impact of the lift crash, building glasses — from the 5th floor to theground floor — smashed and their broken pieces fell on the people staying on different floors,leaving many injured.

18

Figure 1: Tropical Alauddin Tower Shopping Complex in Uttara after fire explosion

Figure 2: Fire fighting

Figure 3: Rescue operation

19

PART-III

FIRE IN INCIDENT IN TAMPACO FOILS LTD
AT BSCIC INDUSTRIAL AREA, TONGI,GAZIPUR ON 10 SEPTEMBER, 2016
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed Ansary201. The Incident
On 10 September, 2016 at 5:00 am an incident of explosion occurred at the factory building of
Tampaco Foils Ltd in BSCIC industrial area, Tongi, Gazipur, some 20km north of capital Dhaka.
The company manufactures paper backed foils, plugs wrap paper, cigarette paper, filter tipping paper
and printed, metalised and laminated films for different local industrial units as well as multinationalorganisations.

Figure 1: Black plumes of smoke from the building
The explosion triggered a massive fire and led to the partial collapse of the four-storey factorybuilding. The raging blaze reduced the factory to ruins as parts of the upper floors of the four-storey
building caved in. Black plumes of smoke from the building spiralled upward, engulfing the area in
the initial hours of the incident. The explosion at the factory was so strong that it caused large chunksof debris to fly in all directions. Even some windowpanes at a few nearby buildings were broken off
due to the impact of the blast. The factory blaze also engulfed an adjoining five-storey building. A
BUET expert team that visited the site in the afternoon said that the five-storey building too mightcollapse and warned the firefighters against attempting to enter it. Both the buildings are owned by
Tampaco and situated on one compound.

21

Figure 2: Collapsed building of Tampaco Foils Ltd
2. Fire extinguishing
The fire could not be extinguished till 11 September, 2016 because the explosion was huge and thefire triggered by the blast spread quickly because flammable chemicals and oil drums were stored at
the factory. About 150 firefighters of 25 units and around 50 volunteers worked since morning todouse the blaze, but they had to struggle from outside of the building as they could not enter it due tothe chemical containers in the factory. They tried to move into the interior of the building. But theattempt was frustrated by thick smoke and broken chunks of concrete. A fresh fire broke out in thebuilding's western part around 11:00am, forcing rescuers and volunteers to get out of the building.
Additionally, there was no access to the buildings for an effective fire fighting as the compound with
only one entry is surrounded by industrial and residential structures. The buildings were very long inshape and both had deposits of chemicals making fire fighting difficult. They were doing defensive
fire fighting to ensure that the fire did not engulf any other adjoining buildings and structures. Firefighters put out the blaze around 5:00 pm on 11 September 2016, nearly 36 hours after the factory
was engulfed in flames – what authorities blamed on a boiler explosion in the factory.

22

Figure 3: Fire extinguishing operation

Figure 4: Fire extinguishing operation including local and fire service personnel
3. Rescue operation
After dousing the fire, rescue operation was started on 12 September 2016 in the morning. A team of
14 independent engineering brigades joined the rescue operations led by Brigadier General A SM
Mahmud Hasan with heavy equipment on the site. They were assisted by Gazipur City Corporation,
the fire service, Gazipur administration and local police. The rescue operators said that, it may take23

up to two months to remove all the rubble from the Tampaco site because the rubble is even morethan the Rana Plaza debris and there were some drums containing ethyl there too. The operators
lacked the experience in handling such chemicals.

Figure: Initial rescue operation by local people

Figure 5: Rescue operation including local and fire service personnel

24Figure 6: Rescue operation

Figure 7: Rescuer operation including army and fire service personnel

4. Casualties
Established in 1978, the factory has around 350 workers working in three shifts. About 100 people
were working in the morning shift, who were already in a holiday mood as it was their last working
day before the weeklong Eid vacation. But it turned out to be a devastated day in their lives. Local
people started the rescue operation, thus they could rescue some 30 to 40 people alive before the25arrival of the firefighters at the spot. But, the locals could not save those trapped inside because of
the extreme heat of the inferno. Many of the workers were trapped inside the building and begging
for help.
More than 100 people were injured, who were admitted to Tongi 50-bed hospital. Some of them incritical conditions were sent to Dhaka Medical College hospital. Till 11 September, 2016, at least 30
people were killed and another 10 people were still missing. 21 died at the scene and the rest
succumbed to their wounds at Dhaka Medical College Hospital (DMCH) and other health facilities
including Tongi Government Hospital, Uttara Adhunik Medical College Hspital and Kurmitola
Medical College Hospital. Parts of the debris fell on the road in front of the structure killing threerickshaw passengers instantly. The rescuers recovered more bodies from the spot as the rescue
operation went on. By 27 September 2016, the death toll rose to 39 and another 10 people were still
missing.
Ministry for Labour and Employment declared to give Tk 2 lakh to each family of the deceased andalso promised to give Tk 1 lakh each injured worker to ensure proper medical treatment for them.
5. Investigation of the incident
Separate probe committees were formed to investigate the incident. The Fire Service and Civil
Defence Department formed a five-member probe body with its Deputy Director as the head to file areport within 10 working days. The BSCIC formed a three-member committee with its regional
director of Dhaka to submit its report within seven days. Meanwhile, Gazipur district administration
also formed a five-member probe committee to submit its report within 15 working days. The
Department of Inspection for Factories and Establishments (DIFE) also formed a three-member bodyto find out the cause of the incident within seven days.
The factory was risky since it was housed in a 40-year-old building. Initially it was assumed that thefire was triggered by a boiler explosion. The Office of the Chief Inspector of Boilers initially ruledout the possibility of the fire being caused by a boiler explosion. But the inspection at the factory site
revealed that there was no damage to the two boilers of the packaging factory. Thus, the authority
dismissed reports that the fire at Tampaco Foils was caused by a boiler explosion. In contrary, thesurvivors from the disaster claimed that it was an explosion during gas leak that brought the factorydown. A survivor claimed that he could hear gas leaking and smelled its odour on the fateful day. On
24 September 2016, the Titas Gas Transmission and Distribution Committee concluded after
assessment that, did not find faults in gas pipeline responsible for the incident because the pipeline
was found unharmed. They assumed that the explosion was resulted due to chemical explosion.
Moreover gas supply to the factory was suspended within half an hour of the incident, although they26

found evidence of gas use beyond the approved limit. The factory was consuming gas at least twice
the permitted amount at the time of the incident.

PART-IV

MEASUREMENT OF ELECTRICALRESISTIVITY WITHIN A POWER PLANT
AREA
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Pushpendue Biswas
Mehedi Ahmed Ansary27

Test Point 01:
The electrode spacing was 2 m. Resistivity tomography for Test point 01 was measured with Wennerarray. The validity of Wenner ERT section of Test point 01 is supported by good low RMS error of
1.38% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of 0.226-20 Ω m. The soil profile is shown in the Table 1. This profile
exists two soil layers. The top layer exist clayey filling sand from 0 to 3.0 m which was saturated
during the test by rain water (the resistivity pseudosection shows water in the resistivity model on thesurface level). The second layer exist clay and sand mixture from 3.0 to 7.0 m almost. Figure 1
shows the model resistivity of ERT at Test point 01.

Figure 1: Model resistivity of ERT at Test point 01
Table 1: Electrical Resistivity Tomography (ERT) result at Test point 01
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.0

Clayey filling Sand

0.226-3.69

3.0 to 7.0

Clay and Sand mixture

3.69-20

28

Test Point 02:
The electrode spacing was 2 m. Resistivity tomography for Test point 02 was measured with Wennerarray. The validity of Wenner ERT section of Test point 02 is supported by good RMS error of
37.8% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of 0.25-12 Ω m. The soil profile is shown in the Table 2. This profile
exist mixed soil layers. It could be defined as one layer of combination of clay and sand mix. Figure
2 shows the model resistivity of ERT at Test point 02.

Figure 2: Model resistivity of ERT at Test point 02
Table 2: Electrical Resistivity Tomography (ERT) result at Test point 02
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 7.0

Clay and Sand mixture

0.25-1229

Test Point 03:
The electrode spacing was 2 m. Resistivity tomography for Test point 03 was measured with Wennerarray. The validity of Wenner ERT section of Test point 03 is supported by good low RMS error of
1.13% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of 3.41-494 Ω m. The soil profile is shown in the Table 3. This profile
exists two soil layers. The top layer exist clay and sand mixture from 0 to 3.0 m almost. The second
layer exist clay from 3.0 to 7.0 m almost. Figure 3 shows the model resistivity of ERT at Test point
03.

Figure 3: Model resistivity of ERT at Test point 03
Table 3: Electrical Resistivity Tomography (ERT) result at Test point 03
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.0

Clay and Sand mixture

3.41-250

3.0 to 7.0

Clay

8.0-58.630

Test Point 04:
The electrode spacing was 2 m. Resistivity tomography for Test point 04 was measured with Wennerarray. The validity of Wenner ERT section of Test point 04 is supported by good low RMS error of
9.6% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of 2.45-778 Ω m. The soil profile is shown in the Table 4. This profile
exists two soil layers. The top layer exist clay and sand mixture from 0 to 3.0 m almost with water
saturation. The second layer exist clay from 3.0 to 7.0 m almost. Figure 4 shows the model resistivityof ERT at Test point 04.

Figure 4: Model resistivity of ERT at Test point 04
Table 4: Electrical Resistivity Tomography (ERT) result at Test point 04
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.0

Clay and Sand mixture

3.41-250

3.0 to 7.0

Clay

8.0-100

31

Test Point 05:
The electrode spacing was 2 m. Resistivity tomography for Test point 05 was measured with Wennerarray. The validity of Wenner ERT section of Test point 05 is supported by good low RMS error of
29.2% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of .316-50 Ω m. The soil profile is shown in the Table 5. This profile
exists two soil layers. The top layer exist clay and sand mixture from 0 to 3.5 m almost with very
high water saturation. The second layer exist clay from 3.5 to 7.0 m almost. Figure 5 shows themodel resistivity of ERT at Test point 05.

Figure 5: Model resistivity of ERT at Test point 05
Table 5: Electrical Resistivity Tomography (ERT) result at Test point 05
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.5

Clay and Sand mixture

1.0-6.0

3.5 to 7.0

Clay

1.0-4032

Test Point 06:
The electrode spacing was 2 m. Resistivity tomography for Test point 06 was measured with Wennerarray. The validity of Wenner ERT section of Test point 06 is supported by good low RMS error of
15.2% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of .28-40 Ω m. The soil profile is shown in the Table 6. This profile
exists two soil layers. The top layer exist clay and sand mixture from 0 to 3.5 m almost with very
high water saturation. The second layer exist clay from 3.5 to 7.0 m almost. Figure 6 shows themodel resistivity of ERT at Test point 06.

Figure 6: Model resistivity of ERT at Test point 06
Table 6: Electrical Resistivity Tomography (ERT) result at Test point 06
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.5

Clay and Sand mixture

1.0-8.0

3.5 to 7.0

Clay

10-40

33

Test Point 07:
The electrode spacing was 2 m. Resistivity tomography for Test point 07 was measured with Wennerarray. The validity of Wenner ERT section of Test point 07 is supported by good low RMS error of
15.2% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of 2.35-520 Ω m. The soil profile is shown in the Table 7. This profile
exists two soil layers. The top layer exist filling sand from 0 to 3.5 m almost. The second layer exist
clay from 3.5 to 7.0 m almost. Figure 7 shows the model resistivity of ERT at Test point 07.

Figure 7: Model resistivity of ERT at Test point 07
Table 7: Electrical Resistivity Tomography (ERT) result at Test point 07
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.5

Filling Sand

100-250

3.5 to 7.0

Clay5.07-70

34

Test Point 08:
The electrode spacing was 2 m. Resistivity tomography for Test point 08 was measured with Wennerarray. The validity of Wenner ERT section of Test point 08 is supported by good low RMS error of
7.8% for the 3rd iteration. The depth of the investigation was found of about 7.0 m. The resistivity’salong the profile span a range of 0.56-200 Ω m. The soil profile is shown in the Table 8. This profile
exists two soil layers. The top layer exist clay from 0 to 3.5 m almost with very high water
saturation. The second layer exist clay and sand mix from 3.5 to 7.0 m almost. Figure 8 shows themodel resistivity of ERT at Test point 08.

Figure 8: Model resistivity of ERT at Test point 08
Table 8: Electrical Resistivity Tomography (ERT) result at Test point 08
Depth (meter)

Soil Type

Resistivity Range (Ω m)

0 to 3.5Clay

1.0-12

3.5 to 7.0

Clay and sand mix

13-17035

PART-V

ASSESSMENT OF UNDERLYING CAUSES OF
FIRE RISK IN OLD DHAKA: A CASE STUDYOF ISLAMBAG AREA IN WARD NO. 65,
DHAKA SOUTH CITY CORPORATIONBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed Ansary36

1. INTRODUCTION
Incident of fire is hazardous when it results in loss of human life and economy. In urban areas theeffect of fire hazard is much more in comparison to other areas because of the development pattern
and land use. In Dhaka, the capital city of Bangladesh, fire hazards cause huge life and economic
loss every year (BSFCD). The causes behind such large scale fire hazards in the city are: violation ofbuilding codes and non-compliance with the Firefighting and Extinguishing Law, dense building
concentrations, lack of safety measures, narrow roads, flammable building materials and electricalsystem as well as the lack of resources to raise awareness and response skills (BFSCD, 2003).
Particularly in Old Dhaka, incidents of fire hazards are more frequent than any other part of the city.
In this area, most of the buildings are of mixed use, where the ground floor and/or the first floor areused for small factories like chemical, plastic, rubber etc., mechanical shop, welding shops,
warehouse and food shops, etc. Rests of the floors of the buildings are used for residential purpose
mainly for the workers of the factories and shops. Thus, fire hazard vulnerability of Old Dhaka isvery high.
In case of fire incidents in Dhaka city, firefighting is a very important job, but fire prevention is morecrucial to prevent an actual fire accident from happening. In general, fire protection equipments andthe use of firefighting tools are given more emphasis, neglecting the importance of practicing fire
preventive measures. The purpose of fire prevention plan is to eliminate the causes of fire and toprevent loss of life and property by fire (OSHCON, 2006), for which a clear understanding ofunderlying cause of fire are required to be identified to take initiatives thereby. Bangladesh, as adeveloping country, cannot afford the huge amount of loss caused by fire accidents every year in
Dhaka city, particularly in Old Dhaka. So, this study aims at assessment of the reasons of fire risk in
Old Dhaka to pave the way for the preparation of a fire prevention plan for Old Dhaka. In this study,
Islambag area of Ward No. 65 (Figure 1) of Old Dhaka was selected for the assessment. The causes
are that, fire incidents are very common phenomenon in this area and this area is one of mostvulnerable areas to fire hazard because of its traditional land use and population density. Thus in thisstudy, assessment of fire risk was done to find out potential underlying causes behind fire hazard inIslambag area of Ward 65 of Old Dhaka.

37

Figure 1: Study Area (Ward No. 65 of Dhaka city) (Source: Dhaka City Corporation)
The main reasons for any fire hazard are the sources of fire hazard and other factors accelerating theincident. Fires require fuel, an adequate oxygen supply, and an ignition source, i.e., the Fire Triangle,
which when brought together, cause fires (Figure 2). Fire prevention can be accomplished bymaintaining control over one or more of these three required elements (UoC, 2005).

Figure 2: Fire triangle (Source: UoC, 2005)
An ignition source is something that can cause an accelerant or flammable material to ignite, e. g.
unsafe electrical conditions, machines and equipments, hot work, careless smoking etc. (Margentino,& Malinowski, 1992). The ignition sources can pose a fire hazard if they are placed near the
combustible materials (EHSS, 2011).


Unsafe Electrical Conditions



Machines and equipment



Hot work

Careless Smoking
38Anything that can burn is potential fuel for a fire or, in some cases, an explosion (Margentino, &Malinowski, 1992). Certain types of substances can ignite at relatively low temperatures or pose arisk of catastrophic explosion if ignited (OSHCON, 2006)


Combustible Materials

Flammable Materials



Accelerants (OSHCON, 2006; EHSS, 2011, Margentino, & Malinowski, 1992).

The main source of oxygen for a fire or explosion is in the general body of air. There are also othersources of oxygen, such as bottled oxygen, compressed air distribution systems and chemicals that
release oxygen when heated (oxidizing agents) such as hydrogen peroxide etc. (HSE, 2012).
Beyond the main sources of fire, there are other factors which are not responsible for ignition of afire, but fire protection and ease of firefighting to reduce loss depend on these factors.
 Structural condition Safety measures
In this study, thermal image captured by thermal imaging camera has been used for identification ofignition sources of fire in the factories located in the study area. A thermal imaging camera is aunique and non-contact tool utilizing infrared thermography which is the art of transforming an
infrared image into a radiometric one allowing temperature values to be read from the image. Thus
the tool produces thermal image indicating the exact location of energy losses through scanning andvisualizing the temperature distribution of entire surfaces quickly and accurately providing precise
and convincing argumentation (FLIR, 2011a & 2011b).
Thermal imaging cameras are powerful and noninvasive tools for monitoring and diagnosing these
conditions, identifying problems early, allowing them to be documented and corrected before
becoming more serious and more costly to repair (FLIR, 2011a).
Electrical devices are usually rated in power indicating the maximum amount of energy the device
can consume without being damaged (Taib, Jadin, & Kabir, 2012). If an electrical equipment is
operated above its specifications, this results in lower efficiency of the device, causing the energy to
be spent in generating heat (FLIR, 2011b, Haidar, Asiegbu, Hawari, & Ibrahimm, 2012, and Taib,
Jadin, & Kabir, 2012). Faulty connections and wiring indicate a loose, over tightened or corroded
connection with increased resistance and faulty fuses indicate its saturated capacity, which thus
become warm (FLIR, 2011b). If the faulty electrical equipments are left unchecked, heat can rise to
the point where connections start to melt resulting in sparks to start a fire (FLIR, 2011a & 2011b).
39

The radiated heat from an electrical device can be measured on the infrared spectral band of theelectromagnetic spectrum using thermal imaging (FLIR, 2011b, Haidar, Asiegbu, Hawari, &Ibrahimm, 2012). If the difference in temperature between similar components under similar loads
exceeds 15 °C (~25 °F), it indicates requirement of immediate repairs (FLIR, 2011b).Thus, any ofthe electrical problems can be avoided with the use of a thermal imaging camera, helping to detect
anomalies that would normally be invisible to the naked eye and to solve problems before production
goes down or a fire occurs (FLIR, 2011b).

Figure 3: Use of thermal image in detecting faulty electrical instruments (Source: FLIR, 2011a &2011b)
Mechanical systems heat up if there is a misalignment at some point in the system, or whenmechanical components become worn and less efficient. Again, increased surface temperatures canbe the result of internal faults. Excessive heat can also be generated by friction in faulty bearings due
to wear, misalignment or inadequate lubrication. When these overheated machines come to contact
with electrical equipments or any combustible or flammable materials, this results in fire to ignite.
Thermal images help to inspect overheated mechanical installations in the factories. Interpretation of
results should be based on comparison between components operating in similar conditions undersimilar loads (Source: FLIR, 2011b).

40

2 METHODOLOGY OF THE STUDY

The research has been conducted with the following methodology:
2.1 STUDY DESIGNIn Old Dhaka fire incidents are very common, but for lack of knowledge about the reasons behindsuch frequent fire incidents proper initiatives for the fire prevention cannot be taken for the area.
Thereby, objective of the study was defined to find out the causes of fire incidents in Old Dhaka.
Then methodology of the study was defined based on literature review.

Islambag

Figure 4: Fire risk zone in Ward 65
2.2 STUDY AREA SELECTION
The Islambag area of Ward No. 65 of Old Dhaka is selected as the study area. The total area of Ward
No. 65 is 118.1668 acres (0.478 Square Kilometer). Ward No. 65 is divided into three risk zones
including high risk zone, moderate risk zone and low risk zone according to their land use fromexpert opinion (Figure 4). High risk zone is 52.84 acres (44.72%) where dominant land use areplastic processing industries; moderate risk zone is 30.89 acres (26.14%) where dominant land use
are processing factory and different warehouse (plastic warehouse, cattle food storage etc), and low
risk zone is 27.95 acres (23.65%) where dominant land use are residential use with commercial
facilities (retail shop, office, bank and storage) (calculated from GIS). Islambag area lies in the highrisk area as the livelihoods of the inhabitants of this area are primarily based on plastic processing
industries.

41

2.3 PREPARATION OF QUESTIONNAIRE
For achieving the objectives, depending on the literature review a questionnaire for the study has
been designed which has been modified on the basis of findings from pilot survey.
2.4 FINDING OUT REASONS BEHIND FIRE HAZARD
The reasons behind fire hazard in the study area was assessed by identification and observation of thesources of fire hazard, i.e. ignition sources, sources of ignition, fuel and oxygen, assessment ofstructural condition, and identification and observation of availability of safety measures.
Considering these factors, the methodology for fire hazard assessment was developed, which
involves both questionnaire survey and visual assessment.
3. REASONS OF FIRE HAZARD IN THE STUDY AREA
Fire hazards are mainly initiated in the factories or small scale industrial buildings in the study area.
In this study, 20 number of buildings have been surveyed which are mainly factories or small scaleindustrial buildings. In the following section of the report, detailed findings from the survey havebeen described.
3.1 GENERAL CONDITION OF THE BUILDINGS
Number of storey of the surveyed buildings ranged from one to seven. Table 1 shows the frequencyof buildings surveyed with respect to occupancy and number of storey.
Table 1: Frequency of the building surveyed with respect to building occupancy and number offloorsNo. of floors
Building
occupancy
Welding Shop
Plastic Factory
Plastic Storage
Machine Shop
Welding shop and plastic storage
Welding shop and residential use
Machine shop and residential use
Plastic storage and residential use
Plastic factory and residential
Plastic shoe factory
Machine shop and plastic storage
Plastic shoe factory and residential
Total

No. of floors
1 Floor 2 Floors Greater than 2 floors
1
7
1
1
0
0
0
0
0
1
0
0
11

0
0
0
0
1
1
0
0
0
0
1
0
3

0
0
0
0
0
1
2
1
1
0
0
1
6

Total
1
7
1
1
1
2
2
1
1
1
1
1
20

42

3.2 IGNITION SOURCES OR SOURCES OF HEAT
Figure 5 shows ignition sources of fire in the surveyed buildings with respect to number of buildings
containing the source. The main ignition sources in the surveyed buildings are the unsafe electricalconditions. In the study area, the overhead electric supply pole and wires are arranged in muchdisorganized way, which may cause rapid spread of fire in the area. Almost all the surveyedbuildings pose similar electrical unsafe conditions which include: improper wiring system, defective
switches and outlets, defective fuses, cable conduit on wall not clipped properly and low quality
electrical equipments, among which use of low quality equipments, defective wiring system, anddefective cutouts and fuses are most common (Figure 5).

Figure 5: Fire ignition sources in the study area
Among the surveyed buildings, plastic factories and machine shops contain machines andequipments. Most of the machines are not lubricated properly causing overheat. Thus, nine buildings
among twenty have the problem of overheated machine (Figure 5). Moreover, for lack of proper
maintenance, the machines and equipments used in the factories have layer of oil cover which
accelerates the possibility of ignition of fire. In these factories, the electric equipments and machines
are observed in close proximity, which increase the risk of fire hazard.
In the welding shops, the operations involve hot works which produce open flame. In all thesurveyed buildings, careless smoking is very common according to the workers. Other significant
ignition source that was observed in one of the plastic storage is the use of candle light at the time ofload shedding. Close proximity of the stored plastic materials and candle light may also cause a fire
to initiate. One of these factors may contribute to ignition of fire in the buildings and the study area.

43

3.3 SOURCES OF FUEL
Figure 6 shows sources of fuel of fire in the surveyed buildings with respect to number of buildings
containing the source. Most common combustible materials used, produced and preserved in thesurveyed buildings are plastic products and materials soaked in oil (Figure 6). Again close proximityof ignition sources and fuel sources increase the risk of fire hazard in the area.

Figure 6: Sources of fuel of fire in the study area
3.4 SOURCES OF OXYGEN
For assessment of sources of oxygen in the study area, the air circulation systems in the buildings
were assessed. In plastic factories and storages, smoke and heat vents are installed, whereas inmachine shop and welding shops there are no sufficient ventilation systems. Thus among twenty
surveyed buildings thirteen buildings have smoke and heat vents, among which seven have sufficientventilation. In storages of plastic materials, heat vents are mainly located in the walls which aremostly small in size, very few in numbers and are placed in distant locations. In plastic factories, heatvents are mainly located in the ceilings which are mostly large in size as the plastic production
activity creates greater heat and smoke. In all the cases, smoke and heat vents are kept open. Thus
among thirteen buildings, Thus, most of the buildings lack proper air circulation system, which may
result in rapid spread of fire in the area.
3.5 STRUCTURAL CONDITION
Spreading of fire and success of fire rescue and firefighting operation largely depend on structural
condition. The structural conditions includes, i.e. building material, condition of wall and roof,
condition of exit door, condition of stair, etc. Figure 7 shows components of building structures inthe surveyed buildings according to building material with respect to number of buildings. The
structures made of brick have heat resistance time of three hours and concrete have heat resistancetime of three hours (Brick Industry Association, 2008 and Beall, 1994). Thus the buildings withcomponents made of brick are safe for fire hazard. The buildings of single storey are constructed44

with tin roof which are highly vulnerable to fire. The buildings with two storeys are constructed withwooden roof and the second floors are constructed of tin and wood, which are also highly vulnerable
to fire hazard.

Figure 7: Component of structure with respect to material in the surveyed buildings
The minimum safe dimension of exit doors is minimum two feet width and minimum seven feetheight, which is required for safe evacuation. In all of the factories, the exit doors are steel shutter,
which are wide enough. Thus, sixteen out of twenty buildings have safe exits which are suitable for
evacuation. Figure 8 shows condition of stairs in the surveyed buildings with respect to number ofbuildings.

Figure 8: Condition of stair in the surveyed buildings
Among twenty surveyed buildings nine have stairs, among which seven buildings have concrete stair
and two have steel stairs. Steel stairs are highly vulnerable to fire hazard due to its heat capacity.
Stairs are the weakest part of a construction, whereas in the surveyed buildings the stairs are in
deteriorated condition. Among nine buildings with stair, four do not have landing ventilation, three
have obstruction in stairway and four have handrails. Thus, only two are suitable with respect togeneral condition of stair and seven are suitable with respect to dimension. So, conditions of thestairs are required to be improved. Thus, structurally the surveyed buildings are highly risky to fire
hazard.
45

3.6 AVAILABILITY OF SAFETY MEASURESIn most of the cases, width of access roads is on an average 15 ft. Thus, in case of any fire incident,
fire vehicles will be able to enter the area through the adjacent roads, though they will have tocontinue the firefighting operation on feet within the narrow access roads. Among twenty surveyedbuildings, only two have firefighting operation system. Again only six buildings among twenty havewater source through underground and overhead tank due to their mixed use with residential use.
Moreover, capacities of these water sources are not sufficient. According to Bangladesh National
Building Code, buildings should have underground reservoir of 50000 liters and overhead reservoirof 25000 liters (BNBC, 2006). Thus, safety measures are not sufficient in the buildings.
4. PREVENTION STRATEGY
Based on the findings of the study, fire prevention plan can be developed for the small scaleindustrial buildings of Old Dhaka to avoid any fire or explosion risks by eliminating either the
potential ignition sources or potential fuel sources, or both (HSE, 2012). However, it is not possible
to eliminate all the sources, so strategies can be developed to reduce fuel loads, eliminate ignition
sources or prevent the fuel/ignition interaction by keeping potential ignition sources apart frompotential fuel, then fire loss and human death and injury can be reduced (HSE, 2012). Particular
strategies to prevent fire hazard in Old Dhaka are described below:


Faulty electrical issues should be taken care of. The relevant strategies should include:
correction and improvement of wiring system, replacement of damaged wiring, fuses,
switches and plugs, avoid use of extension cords and ensure proper covering of all outlets,junction boxes and electrical panels.



Machines and equipments should not be used by overloading their capacities to prevent
overheating. Other measures should include: cleaning of all work areas of oil to prevent
buildup and all power equipments should be turned off or unplugged after use.



Hot works, i.e. welding or working with an open flame or other ignition sources, should bedone in controlled and well-ventilated areas.

Smoking should be strongly prohibited in the work place.

Combustible or flammable materials should be kept in safe distance from the potential
ignition sources and should be stored in safer places.

Well ventilation in workplace should be ensured.

Regular inspection in the factories should be ensured to keep the work place free of dust. The
equipments should be kept in good working order. Electrical equipments should be turned off
when not in use.
46



Minimum fire protection instruments should be stored in the factories. Based on the type ofsource of a fire hazard, different fire protection instruments should be used, as some fire may
be sensitive to certain types of fire extinguishers. Based on source of fire, fire incidents may
be classified into five classes, for which certain extinguishing media may be required, whichis shown in table 2.

Table 2: Classification of fire with respect to source and required extinguishing media
Classof fireA

Extinguishing
media
Extinguisher
that
Materials causing therequiredandtheirshould not be usedfirecharacteristics
Ordinary combustible Water and dry chemicals:
material: wood, paper, Douse flames quickly andrags, rubbish, rubber prevent spreading of fire.
and plastic.

Carbondioxide,dry Water: Use of waterchemicals,
foam
and may spread the fire.
halogenatedhydrocarbons:
Limit supply of air.
Water spray: to cool thecontainers which are likely tocatch fire.

B

Flammableor
combustible gases andliquids:
gasoline,kerosene,thinners,
paints,greaseandsimilar materials.

C

Carbon dioxide or dry Water and foam: They
cause
short
powders:
Non-conducting may
circuiting,electricmaterials.
shock and damage tothe equipment.
Normal extinguishing
Metals:Magnesium Special extinguishing agents.
agents:Increase
sodium,titanium,
intensity of fire.
potassium, zirconium.

DElectric equipments

Source: Adopted from AmeriCares, n.d.
5. CONCLUSION
After an in depth assessment of the buildings with commercial and industrial use in Old Dhaka, it
can be said that the buildings are vulnerable to fire hazard and the overall condition of buildings are
not suitable for firefighting. Although this study was not conducted on a large number of building
samples, it represents the miserable condition of the buildings in Old Dhaka increasing the risk offire hazards in the area. It is not possible to eliminate all the sources of fire hazard in the area, but atleast some initiatives can be taken to minimize the loss. Thus, for improving the condition some fire
prevention strategies have been suggested in this study. For further development in the area, all47

buildings should follow the provision provided by Bangladesh National Building Code andBangladesh Fire Service and Civil Defense during construction. To prevent violation of regulation
strict inspection and actions are required from corresponding authority. The good practices of fire
hazard prevention in the building codes of other countries need to be studied and adopted according
to Bangladesh’s context. In addition, to create public awareness, workshops and seminars may bearranged. Electronic and printing media can play an important role for increasing awareness. A
pragmatic fire safety plan may be developed for all the buildings with the help of Bangladesh Fire
Service department.
REFERENCES
Bangladesh Fire Service and Civil Defense (BFSCD). (2003). Fire Fighting & Extinguishing Law.
Bangladesh National Building Code (BNBC). (2006). Published by HBRI-BIDS.
AmeriCares. (n.d.).Fire Prevention and Fire Safety: Health Worker Safety Training Module 5.
Retrieved October 11, 2014, from:http://www.americares.org/assets/downloads/pdf/modules/hws/HWS-5-fire-safety.pdf
OSHCON. (2006). Sample Written Program for Fire Prevention Plan. Occupational Safety and
Health Consultation Program (OSHCON), Texas Department of Insurance, Division of Workers’
Compensation, Publication No. HS03-013A (1-06). Retrieved October 11, 2014, from:http://www.tdi.texas.gov/pubs/videoresource/ofirepreventio.doc
EHSS. (2011). Fire Prevention Planning. Environmental, Health and Safety Services (EHSS),
Virginia Polytechnic Institute and State University. Retrieved October 11, 2014, from:http://www.ehss.vt.edu/uploaded_docs/200802261709470.Fire%20Prevention%20Planning.ppt
UoC. (2005). Basic Fire Prevention Measures. Environmental Health and Safety, Division ofAgriculture and Natural Resources, University of California, Safety Note #72. Retrieved October
11, 2014, from:http://safety.ucanr.org/files/1468.pdf
Margentino, M. R., & Malinowski, K. (1992). Fire prevention and safety measures around the Farm.
Rutgers Cooperative Extension, University of New Jersey: document FS608. Retrieved October
11, 2014, from:http://nasdonline.org/static_content/documents/1048/d000843.pdf

48

HSE. (2012). Guidance on the prevention and control of fire and explosion at mines used for storageand other purposes. Great Britain: Health and Safety Executive (HSE). Retrieved October 11,
2014, from: http://www.hse.gov.uk/mining/festorage.pdf
Beall, C. (1994). Calculating Masonry's Fire Resistance. Mag. Masonry Constr., 7(8), 372-391.
Retrieved 24 November, 2014 from:http://www.masonryconstruction.com/Images/Calculating%20Masonry%27s%20Fire%20Resista
nce_tcm68-1375295.pdf
Brick Industry Association. (2008). Technical Note 16: Fire Resistance of Brick Masonry. Brick
Industry Association, Reston, Virginia. Retrieved 24 November, 2014 from:http://www.gobrick.com/portals/25/docs/technical%20notes/tn16.pdf
FLIR. (2011a). Thermal Imaging Guidebook for Building and Renewable Energy Applications.
FLIR Systems AB.
FLIR. (2011b). Thermal Imaging Guidebook for Industrial Applications. FLIR Systems AB.
Haidar, A., Asiegbu, G. O., Hawari, K., & Ibrahim, F. A. (2012). Electrical defect detection inthermal image. Advanced Materials Research, 433, 3366-3370. Retrieved 24 November, 2014
from:http://ro.uow.edu.au/infopapers/2315/
Taib, S., Jadin, M., S., & Kabir, S. (2012). Thermal Imaging for Enhancing Inspection Reliability:
Detection and Characterization. In Prakash R., V. (Ed.). Infrared Thermography. InTech, ISBN:
978-953-51-0242-7.

Retrieved

24

November,

2014

from:

http://www.intechopen.com/books/infrared-thermography/thermal-imaging-forenhancinginspection-reliability-detection-and-characterization

49

PART-VI

SEISMIC MICROZONATION OF COX'S
BAZAR MUNICIPAL AREA BANGLADESHBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Afifa Imtiaz
Mehedi Ahmed Ansary

50

1.

INTRODUCTION

Cox's Bazar Municipal is located in the Southeastern part of Bangladesh, beside the Bay of Bengal under the district Cox's
Bazar. The area is famous for her outstanding natural beauty. The district has an area of 2491.9 sq km with a population of
1.8 Million (BBS, 2001). Cox's Bazar municipality covering an area of 6.85 sq. km is located at 21.58°N, 92.02°E. Cox’s
Bazar falls in zone 2 with a seismic coefficient of 0.15g. Recent earthquakes in adjoining areas of Cox’s Bazar indicate awarning that the people of that area should take adequate measures against earthquakes.
Anbazhagan and Sitharam (2010) presented seismic site classification using boreholes and shear wave velocity andassessed the suitable method for shallow engineering rock region. Islam and Hossain (2010) estimated liquefaction potentialof selected reclaimed areas of Dhaka city based on standard penetration test and shear wave velocity. Motazedian et al.
(2011) applied four different seismic methods which were down hole interval vs. measurements at 15 borehole sites, seismic
refraction–reflection profile measurements for 686 sites, high-resolution shear wave reflection “landstreamer” profiling for
25 km in total, and horizontal-to-vertical spectral ratio (HVSR) of ambient seismic noise to evaluate the fundamental
frequency for ∼400 sites for development of a Vs30 (NEHRP) map for the city of Ottawa, Ontario, Canada. Louie et al.
(2011) made earthquake hazard class mapping by Parcel in Las Vegas Valley which included more than 10,000
measurements that classify individual parcels on the NEHRP hazard scale. Another earthquake hazard class mapping by
Parcel was made by Louie et al. (2012) which included 10,721 surface-wave array measurements that classify individual
parcels on the NEHRP hazard scale. Cox et al. (2012) worked on frozen and unfrozen shear wave velocity seismic siteclassification of Fairbanks, Alaska which was based on 59 shear wave velocity (Vs) profiles collected using the spectral
analysis of surface waves (SASW) method. Mohanty and Patra (2012) assessed liquefaction potential of pond ash at Panipat
in India using SHAKE2000 where the liquefaction analysis of pond ash was carried out by using Seed and Idriss method and
1-D ground response analysis. Irfan et al. (2012) worked on local site effects on seismic ground response of Dubai-Sharjah
metropolitan area where dynamic properties of selected soil profiles were evaluated using empirical relations between
Standard Penetration Test (SPT) N-values and shear wave velocity (Vs). Manne and Satyam (2013) estimated the local site
effects using microtremor testing in Vijayawada city, India where microtremor surveys were carried out at 75 different
locations in the Vijayawada urban area and analysis was carried out using the Nakamura technique. Natural Resources
Canada (NRCan) (2013) adapted Hazus for seismic risk assessment in Canada which was a standardized best-practicemethodology developed by the US Federal Emergency Management Agency (FEMA) for estimating potential losses from
common natural hazards, such as earthquakes, floods, and hurricanes. Thaker and Rao (2014) worked on seismic hazard
analysis for urban territories at Ahmedabad region in the state of Gujarat, India where earthquake data has been analyzed
statically and the seismicity of the region is evaluated by defining 'a' and 'b' parameters of the Gutenberg-Richter
relationship. Desai and Choudhury (2014) worked on deterministic seismic hazard analysis for Greater Mumbai, India where
the seismic sources were identified from the seismotectonic atlas of India within the control region of 300 km radius aroundMumbai City and the epistemic uncertainty involved in estimation of different input parameters was accounted within a logic
tree framework. Sil and Sitharam (2016) researched on detection of local site conditions in Tripura and Mizoram using the
topographic gradient extracted from remote sensing data and GIS techniques where Peak Ground Acceleration (PGA) at the
bedrock for the states of Tripura and Mizoram in NE India was estimated using Probabilistic Seismic Hazard Analysis(PSHA), which considered linear sources and events (from 1731 to 2010) with appropriate ground motion prediction
equations applicable for NE India.
In this study, for microzonation purposes, bore holes with SPT data and historical large earthquakes were used as
scenario events. From attenuation laws, Peak Ground Acceleration (PGA) in the bedrock level was estimated and used todevelop a regional combined seismic hazard map based on site liquefaction, amplification and slope stability.
2.

GEOLOGY OF THE AREA

51

Cox's Bazar town is located at the Middle-West part of the district bounded by the Bakkhali River on the North and NorthEast. The area lies within the Eastern flank of Inani Anticline, trending towards NNW-SSW, whose Western Flank is eroded.
The existing Eastern Flank of the anticline is also in the process of continuous erosion. Figure 1 shows the Surface Geology
of Cox's Bazar Municipal area according to the Geological Map of Bangladesh (Alam et al., 1990). The Western Figure
reveals that the area around the city of Cox's Bazar predominantly composed of Valley Alluvium and Colluvium and Dihing
Formation of Pliocene-Pleistocene age. Rocks of the Pliestoeene, Pliocene and Neogene ages are also exposed in the area.
The exposed rock units are mostly
have been observed from the Geological Map of Bangladesh. To the west of the Municipal Boundary, the strand of coastal
Deposit, Beach and Dune Sand, lies extending towards south. To the East of Beach and Sandstone, there lies another narrowzone of Boka Bil Formation of Neogene age. A slight narrow zone Tipam Sandstone of Neogene age forms the Eastern sideof BokaBil zone. Along the East of Tipam Sandstone zone, another formation of Bedrock from Tipam Group that is Girujan
Clay of Pleistocene and Neogene age lines. The North Eastern boundary of the town consists of Alluvial Deposits of Valley
Alluvium and Colluvium. The south eastern part of the town has basically Dihing Formation Bedrock which is characterized
as yellow to yellowish-grey, massive, fine to medium grained poorly consolidated sandstone and clayey sandstone. Dupi Tila
Formation of Pleistocene and Pilocene age lies to the south of Dihing Formation which might have a slight influence in thesurface geology of the city. Dupi Tila is characterized as yellow to ochre, pink, light-brown, light-grey to grayish-white or
bluish-grey sandstone, siltstone and conglomerate.

Figure 1: Geology of Cox's Bazar Municipal (after Alam et al, 1990)

3.

SEISMOTECTONIC SETUP

The generalized tectonic map of Bangladesh and adjoining areas is given in Figure 2. The junction between the platform andthe fore deep running southeast from Mymensingh to Calcutta (the Hinge line) is considered to be a zone of weakness. Some
major earthquakes can be related to the Dauki fault which terminates the fore deep in the Northeast. Most recorded
earthquakes had epicenter further East in Burma. The Himalayan arc can be regarded as one of the most intensely active
seismic regions in this area. In Northeast India, the Shillong plateau and adjacent syntax is between the two accurate
structures are one of the most unstable regions in the Alpine-Himalayan belt. Earthquake data suggest that the basement of
the Indian plate below the Indo-Burma ranges is moving north. Thus the shortening in the overlying rocks is partly
decoupled from the basement. The Main Boundary Thrust (MBT) fault initiated in late Miocene or Pliocene time is regarded
as the present thrust front of the Himalayas and forms the northern margin of the Himalayan foredeep. Bengal Basin isbounded on the East by the western fold belt of the Indo-Burma ranges. The northern and the Central portion of this fold belt
are seismically active. Tripura fault zone is characterized by the high concentration of earthquake events. A number of52morphotectonic lineaments have been identified. Among these the Kopili lineament trending NW-SE is remarkable. At thenorth of this zone Halflong-Dissang thrust is present. Morphotectonic lineaments around the Halflong-Dissang thrust zone
trend NE-SW, E-W and NW-SE. Mikir hill is present to the northeast corner of the Halflong-Dissang thrust, which separates
the Shillong plateau by Kopili fault.

Figure 2: Generalized tectonic map of Bangladesh and adjoining areas (after GSB, 1991)
4.

REGIONAL TECTONICS

According to Molnar and Tapponier (1975), for the past 40 million years the Indian subcontinent has been pushingnorthward against the Eurasian plate at a rate of 5 cm/year, giving rise to the severest earthquakes and most diverse land
forms known. Figure 3 shows continued drift of the Indian plate towards the Eurasian plate. Recently, Bilham et al. (2001)
pointed out that there is high possibility that a large earthquake may occur around the Himalayan region based on the
difference between energy accumulations in this region. There is a seismic gap that is accumulating stress, and a large
earthquake may occur some day when the stress is relieved. Figure 3 shows the estimated slip potential along the Himalaya.
The major earthquakes that have affected Cox’s Bazar area are presented in Table 1.

Figure 3: Estimated slip potential along the Himalaya (after (Bilham et al., 2001)

53

5.

DATA COLLECTION

A total of 26 borelogs were used in this study. SPT were carried out in each boring at nominal 1.5 m intervals to study site
amplification as well as soil liquefaction potential characteristics of municipality area. Among them, twelve subsoil
investigations were carried out by the first author (Imtiaz, 2009). The other fourteen borelogs up to a depth of 30 meters
were collected from a research project on Cox's Bazar District (Dhar et. al. 2008). Figure 4 shows 26 borehole locations.

Table 1: Large earthquakes in and around Cox’s Bazar
Year

Name

Epicentre

Magnitude (M)1762

Arakan Earthquake

50 km northwest of Cox’s Bazar

8.5

1858

Prome Earthquake

Sandaway, Myanmar

7.0

1912

Mandalay Earthquake

Sagaing, Myanmar

7.7

1956

Sagaing Earthquake

Sagaing, Myanmar

7.1

1997

Bandarban Earthquake

Ruma, Bandarban

6.0

1999

Moheskhali Earthquake

Moheskhali Island

5.1

At entire area under Cox's Bazar Municipality necessary data such as subsoil reports and geology, topography etc wascollected from different relevant sources. The GPS locations of all the borehole investigation points and hill soil samples
have been presented on the digitized municipality map and were saved in MS Excel. For assessment of landslide potential
Geological Map and Aerial Photograph were not available in the concerned authorities' office considering this limitation thisstudy was carried out.
For slope stability analysis, hilly regions of this area have been surveyed and data of location, height, and slope havebeen collected (see Figure 5). Where eleven disturbed samples from different locations of the municipal area were collected
for laboratory investigations including specific gravity test, grain size analysis, Atterberg limits, Standard compaction test
and direct shear test.

Figure 4: Cox's Bazar municipal area map showing soil borehole locations

54

6.

ASSESSMENT OF SEISMIC HAZARD

The first step in reducing the risk of the society from earthquake hazard is the assessment of the hazard itself. Seismic
microzonation map for strong-ground shaking, liquefaction, and landslide can play a significant role in mitigating the effectsof earthquake in urbanized regions. The seismic hazard evaluation at a specified site depends upon the definition of thefollowing four models:
Earthquake source model: It is based on geological evidence, Seismic sources are identified and modelled as a point,line, area or dipping plane. In this study, a point source model is used.
Seismicity model: The seismicity of each of the modeled sources is first determined from past data available. The
recurrence relationship relating the size of the past events in terms of Magnitude (M) and Peak Ground Acceleration (PGA)
is derived, the seismicity model used in Molas and Yamazaki (1994) is usually taken aslog(v) =a+b*M(1)log(v) =a+b*log(y)(2)

Where M is the earthquake magnitude and y is the peak ground acceleration. v is occurrence rate per year and a and b areregression constants. These relations can be written as
M= (-log(T)- a)/b(3)log(y)= (-log(T)- a)/b4)

where T (=1/v) is the return period in years. Thus, the above equations represent magnitude and the peak ground acceleration
for a return period of T years.
Attenuation model of ground motion: This describes the transfer of ground motions from the source to a particular site asa function of magnitude, distance and soil conditions. Here, the peak ground acceleration is used to characterize the groundmotion; the attenuation law is in the form
log(y) = b1 + b2 (Ms) - b3 log (r) - b4 (r)(5)

where,=+,

r =the hypo central distance (km),d = the epicentral distance (km),h = the focal depth and Ms is the surface-wave magnitude.
The attenuation law is required to determine the peak ground acceleration at the site for different events and then to
determine the regression constants a and b.

55

Figure 5: Soil sample locations for estimation of landslide potential

Recurrence forecasting model: For practical purposes, earthquakes are considered to be random events, and the Poissonprocess is used, which implies assumptions of stability and independence over time. For a Poisson process this may be
expressed as
p= 1-exp(-vt)(6)

where,
v = the mean annual occurrence rate of events of particular peak ground acceleration over a given time t.
The most common method involves the use of an empirical attenuation relationship. These relationships express a given
ground motion parameter in a region as function of the size and location of an earthquake event. The evaluation of seismic
hazard at a site is carried out only if the number of earthquakes in the area considered (200 km radius) is larger than 10 andthe surface-wave magnitude is equal to or greater than 4.0. In this study evaluation of seismic parameter has been carried out
using the seismic data over an area having a 250 km radius around Cox's Bazar Municipal area (see Figure 6).

Figure 6: Historical Earthquakes around Cox's Bazar Municipality

56

6.1

Selection of Attenuation Law for Peak Ground Acceleration

To select the most suitable attenuation law for predicting rock motions, the formula adopted in the previous studies were
followed (Sabri 2001, Sharfuddin 2001). From these studies, it was found that McGuire (1978) as well as Joyner and Boore(1981) equations follow the PGA trend of most large earthquakes in and around Bangladesh. Since, McGuire equation was
already used for Bangladesh for seismic hazard analysis (Sharfuddin, 2001) and due to its simple form, it was selected forfurther use. The attenuation laws for rock used in this study, are presented below:
PGA (from McGuire) = 0.0306.

PGA (from Joyner & Boore) = 0.0955

.
.

(7)
. .

(8)

Where,
M = Earthquake Magnitude,d = Epicentral Distance,r = Hypocentral Distance andh = Depth
6.2

Regression Analysis

Seismic parameter b was evaluated from G-R relationship (Gutenberg and Richter.1944), a method utilizing extreme,
instrumented and complete catalogs. Linear regression was applied to each site which is taken as the centre of an area of 250
km radius where past earthquakes are likely to occur again. The hazard curves of Mean Annual Rate of Exceedance (v)versus Peak Ground Acceleration (PGA) and Mean Annual Rate of Exceedance (v) versus Earthquake Magnitude (M) weregenerated at the rock levels. The hazard in terms of the rock level PGA values and probable earthquake magnitude
corresponding to return periods of 200 years are quantified from equation 3 and 4 as, 0.18g and 8.3 consecutively. Since thelargest Magnitude earthquake around the 350-450 km radius of the study area exceeds 7.9 and around 250 km radius is 6.5, acut-off Magnitude of 7.5 earthquake was considered as the expected one in 200 years return period and thus used for further
analyses.

7.

SITE AMPLIFICATION ANALYSIS

For site amplification, in this study, the engineering bedrock was assumed to be the layer at which the shear wave velocity(Vs) exceeds 400 m/s, which exist almost 30 m deep from the surface of the study area. The calculations show that the shear
wave velocities at bedrock level vary from 400 m/s to 500 m/s. Vibration characteristics plotted as transfer functions at
different points of the study area were estimated by employing one dimensional wave propagation program SHAKE. The
computations were made in the frequency range 0 to 20 Hz at frequencies every 0.05 Hz interval. The loss of energy ofseismic waves in the soil layers was also considered. The computed results from the site amplification potential analysis
were exported to a GIS environment for further processing and visualization. They were classified into different classes
according to the extent of amplification factors and plotted on the Cox’s Bazar municipal map (see Figure 7).
From the site amplification study, the average amplification factor was found to be 2.3 and 1.7 respectively for extreme
and average conditions. The rock level PGA for return period of 200 years was estimated as 0.18g. Thus the surface level
PGAs calculated by multiplying the rock level PGA with amplification factor were 0.4g at extreme condition and 0.31 g
considering AHSA.

57

Figure 7: Microzonation map based on amplification at fundamental frequencies
8.

LIQUEFACTION ANALYSISThe first step in calculation of liquefaction potential is to determine whether the soil has the potential to liquefy during theearthquake. This analysis is usually carried out by using simplified empirical procedure, originally developed by Seed andIdriss (1971). Since the largest earthquake magnitude has been considered as 7.5, the relevant Magnitude Scaling Factor(MSF) was selected as 1.0. The Factor of Safety against Liquefaction for earthquakes other than that of magnitude 7.5 andcalculated as
FS= FL =

.

MSF

(9)

Where,
CRR7.5= Cyclic Resistance Ratio for the earthquake of magnitude 7.5
CSR= Cyclic Stress Ratio
The severity of foundation damage caused by soil liquefaction depends to a great extent on the severity of liquefaction,
which cannot be evaluated solely by the FL. Liquefaction under the following condition tends to be severe:
I. The liquefied layer is thick
2. The liquefied layer is shallow
3. The FL of the liquefied layer is far less than 1.00
In this method, the factor of safety values, FL (Seed and Idriss, 1971) against resistance to liquefaction have been computed
up to top 20 meters depth for all the boreholes and these values have been subsequently converted into liquefaction potential
index (IL) given by the following equation (Iwasaki et al., 1982):
IL =

(10)

Where,
F(z)= (1- FL);

for FL ≤1.0

F(z)= 0;for FL >1.0

W (z)=(10-0.5z); for z≤20 m
W(z)= 0 ;for z>20m

58

The value of liquefaction potential, IL indicates that a soil mass is susceptible to liquefaction if IL >0 If the value of IL islarge, the soil is very susceptible for liquefaction. Severity of liquefaction is then expressed as shown below:IL=0;

No liquefaction=0-5;

Low liquefaction=5-15;

Moderate liquefaction= >15;High liquefaction

IL has been used to express the measure of liquefaction potential for a particular location and for further zonation of thearea based on a particular range of this index. Table 2 shows the interpretation of liquefaction potential in terms of intensity
and ground susceptibility.
Table 2: Summary of the liquefaction potential index (after Iwasaki et al., 1986)
Liquefaction

Criteria

Explanation

15< ILGround Improvement is

Potential
Highindispensable
Moderate

5< IL

15

Ground Improvement is required.
Investigation of important
structure is indispensable

Low

0< IL

5

Investigation of Important
structure is required.

Very low

IL=0

No measure is required.

Liquefaction resistance factor, FL, for the top 20 m of soil, and the resulting liquefaction potential IL for the 26 sites was calculated.
The flow chart of liquefaction analysis used in this study and the result of Liquefaction potential was provided in tabulated form. The
computed results from the liquefaction potential analysis were exported to a GIS environment and plotted on the Cox's Bazar district map
dividing the study area into different zones according to the ranges of liquefaction potential index values (Table 2). Thus microzonation
maps were developed for liquefaction potential as shown in Figure 8.

Figure 8: Microzonation map based on regional distribution of liquefied areas

59

9.

LANDSLIDE POTENTIAL ANALYSISThe overall stability failure mechanism is development of slip circles resulting in deep sliding surface which is aconventional soil mechanics stability problem. Preexisting slip planes within the soil, cracker material can have a significant
effect on slope stability. Stability analysis is carried out to evaluate the factor of safety against bearing capacity failure. The
program used for stability analysis is XSTABL which is a fully integrated slope stability analysis program. The landslide
potential was categorized as 'high' and 'low" for Factor of Safety being greater than or equal to 1.2 and less than 1.2
consecutively. The corresponding Factor of Safety values have been exported to GIS and plotted on the Cox's Bazar
municipality range. Thus the microzonation map based on landslide potential was developed as shown in Figure 9.

21. 46 N

kK
Ba

N

r
ive
li R
ha

21.45 N

W 01
W 03

W 02

CP

W 08

W 04

W 07

21.44 N
y
Ba

W 06

W 05

al
ng
Be
of

W 09

To
C

hit
ta

go
ng

2

To

1

Ko
la
to
li

al
ng
Be
of

0

H
im
ch
ha
ri

y
Ba

M
oo
re

21.43 Nkilometres
91.95 E

91.96 E

91.97 E

21.42 N
91.98 E

91.99 E

92.00 E

Figure 9: Microzonation map based on landslide potential in Cox’s Bazar Municipality area
10.

SEISMIC HAZARD INTEGRATION

The most important endeavor of this study was the estimation of seismic hazards linked with the local site attributes of soil
amplification, liquefaction, and landslide and then integrating them in such a manner so that a reflection of probable actual
disaster consequences can be represented. It is not feasible to resolve how much of the potential hazard is discretely
attributed by each local site effect; consequently the ultimate regional seismic hazard distribution is established on aweighted average combination of the hazards related with each effect.
The rules for combining the various hazards were based on expert opinion (Stephanie and Kiremidjian, 1994) about therelative accuracy of the hazard information and the behavior of the local geology. It was assumed that the final combined
seismic hazard would be quantified in terms of Modified Mercalli Intensity (MMI). At the end, different possible hazards
were integrated to investigate the combined effects of more than one hazard. The results of the combined hazard analysis
were summarized in Table 3.
Table 3: Final Combined Intensity and affected areas for different hazard combinations
Combined

Combination of Possible Hazards

Intensity

Area
(%)

(MMIF)

X

2.0 times Amplification + High Liquefaction

43.12

2.5 times Amplification + High Liquefaction

35.40

3.0times Amplification + High Liquefaction

7.72

2.0 times Amplification + High Landslide

1.65
6.25

60

2.5 times Amplification + High Landslide
IX

VIII

11.

2.5 times Amplification + Low Liquefaction

0.93

3.0 times Amplification + Low Liquefaction

2.75

2.5 times Amplification + Low landslide

0.23

2.0 times Amplification + Low Liquefaction

1.95

CONCLUSION

This study proposed a methodology for seismic hazard assessment for Cox’s Bazar, Bangladesh. In this study, seismic
microzonation maps were developed on the basis of potential of earthquake occurrences and ground susceptibility toearthquake. SPT data from 26 boreholes were used to study site amplification as well as soil liquefaction potential
characteristics. Using historical seismicity records and attenuation laws of Peak Ground Acceleration (PGA), the bedrock
PGA was estimated as 0.18g for magnitude 7.5 earthquake with 200 years return period. The surface PGA was calculated as
0.41g and 0.31g adopting on First Peak Amplification and Average Horizontal Spectral Amplification, respectively. Theliquefaction potential of the boreholes points were assessed by including these PGAs. Landslide potential was assessed using
a slope stability program. The results obtained from these three analyses, were developed in GIS environment and were
presented in the form of microzonation maps. The final combined hazard (MMIF) is computed as a weighted sum of those
three hazards.

12.

REFERENCES

Alam M.K., Hasan A.K.M. and Khan M.R. (1990) Geological Map of Bangladesh, Geological Survey ofBangladesh,

Govt. of the People's Republic of Bangladesh.
Anbazhagan, P. and Sitharam, T. (2010) “Seismic Site Classification Using Boreholes and Shear Wave Velocity: Assessing
the Suitable Method for Shallow Engineering Rock Region”. GeoFlorida 2010, pp. 1059-1068.
Ansary, M.A., Hussaini, T.M.AI, Sharfuddin, M. and Choudhury, J.R. (1999) "Report on Moheskhali earthquake of July 22,
1999", Earthquake Engineering Series, Research report No. BUET/CE/EQE-99-0l, Department of Civil Engineering,
BUET, Dhaka, August, 1999.
Ansary, M.A. (2009) Earthquake Database of Bangladesh. Unpublished Report. Department of Civil Engineering, BUET,
Dhaka, Bangladesh.
BBS (2001) Population Census 2001: Preliminary report, August, 200 I. Statistics Division, Ministry of Planning, GOB.
Bilham, R., V.K. Gaur and P. Molnar (2001) “Himalayan Seismic Hazard”. SCIENCE. Volume 293.
Cox, B., Wood, C., and Hazirbaba, K. (2012) "Frozen and Unfrozen Shear Wave Velocity Seismic Site Classification of
Fairbanks, Alaska." J. Cold Reg. Eng., 10.1061/(ASCE)CR.1943-5495.0000041, 118-145.
Desai, S. and Choudhury, D. (2014) “Deterministic Seismic Hazard Analysis for Greater Mumbai, India”. Geo-Congress2014 Technical Papers: pp. 389-398. doi: 10.1061/9780784413272.038.
Manne, A. and N. D. Satyam (2013) “Estimation of local site effects using microtremor testing in Vijayawada city, India”.
doi: http://dx.doi.org/10.1680/geolett.13.00033.
Motazedian, J. A. Hunter, A. Pugin, H. Crow (2011) “Development of a Vs30 (NEHRP) map for the city of Ottawa,
Ontario, Canada”. Canadian Geotechnical Journal, 48(3): 458-472, 10.1139/T10-081.

61

Dhar, A.S., Ansary, M.A., Imtiaz, A.B.A.,and Saha, R., (2008) Earthquake Vulnerability Assessment of Cox's
Bazar District, prepared for United Nations Office for Project Services (UNOPS).
Gutenburg, B., Richter, C. F.' (1954) "Seismicity of the earth and associated phenomena", 2nd Edition, Princeton, Princeton
University press.
Imtiaz, A. (2009) Seismic Microzonation Of Cox’s Bazar Municipal Area’, MSc. Engg. Thesis, Department or Civil
Engineering. Bangladesh University of Engineering and Technology. Dhaka, Bangladesh.
Irfan, M., El-Emam, M., Khan, Z., and Abdalla, J. (2012) “Local Site Effects on Seismic Ground Response of Dubai-Sharjah
Metropolitan Area”. GeoCongress 2012: pp. 1869-1878. doi:10.1061/9780784412121.192.
Islam, M. and Hossain, M. (2010) “Earthquake Induced Liquefaction Potential of Reclaimed Areas of Dhaka City”. Soil
Dynamics

andEarthquake

Engineering:pp.

326-332.

doi: 10.1061/41102(375)40.
Iwasaki, T., Tokida, K., Tatsuoka, F. Watanabe, S., Yasuda. S. and Sato K, (1982) “Microzonation for soilliquefaction Potential using Simplified Methods”. 3rd International Microzonation Conference, Proceedings,
1319-1329.
Iwasaki, T. (1986) “Soil liquefaction Students in Japan: State or the Art”. Soil Dynamics and Earthquake Engineering, 5(1),2-68
Joyner, W.B., and D. W. Boore (1981) “Peak horizontal acceleration and velocity from strong motion recorded
including records from the 1979, Imperial Valley. California, earthquake”. Bull. Seism. Soc. Am., 71, 2011-2038.
Stephanie, A. King, and Anne S. Kiremidjian, (1994) Regional Seismic Hazard and Risk Analysis through Geographic
Information System, PhD Thesis, Standford University, USA.
Louie, J., Pullammanappallil, S., Pancha, A., and Hellmer, W. (2012) “Earthquake Hazard Class Mapping by Parcel in Las
Vegas Valley”. GeoCongress 2012: pp. 2746-2755. doi: 10.1061/9780784412121.281.
Louie, J., Pullammanappallil, S., Pancha, A., West, T., and Hellmer, W. (2011) “Earthquake Hazard Class Mapping by
Parcel in Las Vegas Valley”. Structures Congress 2011: pp. 1794-1805. doi: 10.1061/41171(401)156.
McGuire, R. (1978) “Seismic ground motion parameters relations”. Journal of Geotechnical Division, ASCE, Volume 104,
pp. 461 - 490.
Mohanty, S. and Patra, N. (2012) “Assessment of Liquefaction Potential of Pond Ash at Panipat in India Using
SHAKE2000”. GeoCongress 2012: pp. 1829-1838. doi: 10.1061/9780784412121.188.
Molas, G. 1. a,1d F. Yamazaki (1994) "Seismic macrozonation of the Philippines based on seismic hazard analysis". Journalof Structural Mechanics and Earthquake Engineering, JSCE, 489 (1-27), 59-69.
Molnar, P. and P. Tapponier. (1975) “Cenozoic tectonics of Asia, effects of a continental collision”. Science, Volume
189(8), pp. 419-426.
Sabri, S. A., (2001) Earthquake intensity-attenuation relationship for Bangladesh and its surrounding region.
M.Engg. Thesis, BUET, Dhaka,Bangladesh
Seed, H.b. and Idriss, I.M. (1971) “Simplified Procedure for Evaluating Soil Liquefaction Potential”. Journal of the Soil
Mechanics and foundations Division, ASCE, 97(SM9), 1249-1273.
Seed, H. B., and Idriss, L M., (1982) "Ground Motions And Soil Liquefaction During Earthquakes". Earthquake Engineering
Rescarch Institute. Oakland. California, Monograph Series, p. 13.

62

Seed, H. B., I. M. Idriss and L Arango (1983) “Evaluation of liquefaction potential using field performance data”.
Journal of Gcotechnical Engineering. Volume 109, No. 3, pp. 458-482.
Sharfuddin, M. (2001) Earthquake Hazard Analysis for Bangladesh. M.Sc. Engg. Thesis, Bangladesh University ofEngineering and Technology (BUET). Dhaka.
Sil, A. and Sitharam, T. (2016) "Detection of Local Site Conditions in Tripura and Mizoram Using the Topographic
Gradient Extracted from Remote Sensing Data and GIS Techniques." Nat. Hazards Rev.10.1061/(ASCE)NH.15276996.0000228, 04016009.
Thaker, T. and Rao, K. (2014) “Seismic Hazard Analysis for Urban Territories: A Case Study of Ahmedabad Region in theState of Gujarat, India”. Advances in Soil Dynamics and Foundation Engineering: pp. 219-228.

doi:

10.1061/9780784413425.023.

63

PART-VII

EARTHQUAKE RELATED RESEARCH
AND ACTIVITIES IN BANGLADESH
DURING THE LAST SIX YEARS (2010-2016)
BANGLADESH NETWORK OFFICE FORURBAN SAFETY (BNUS), BUET, DHAKA

Prepared By: Mehedi Ahmed Ansary641. INTRODUCTION
In the recent past, Bangladesh has not suffered any damaging large earthquakes, but in thepast few hundred years, several large catastrophic earthquakes struck this area. So far, all the
major recent earthquakes have occurred away from major cities, and have affected relatively
sparsely populated areas. This has limited the human casualty and the economic losses.
However, the 1993 Killari and 2001 Gujarat earthquakes in India has amply demonstrated
that inappropriate construction technology may lead to high casualty levels even for moderate
earthquakes (Sinha and Goyal, 1994).
In 1897, an earthquake of magnitude 8.7 caused serious damages to buildings in thenortheastern part of India (including Bangladesh) and 1542 people were killed. Recently,
Berryman et al. (2014) pointed out that there is high possibility that a huge earthquake will
occur around the Himalayan region based on the difference between energy accumulation inthis region and historical earthquake occurrence (see Figure 1). More recently, Steckler et al.
(2016) suggested that the presence of a locked mega thrust plate boundary under the IndoBurman ranges represents an underappreciated hazard in one of the most densely populated
regions of the world (see Figure 2). The population increase around this region is at least 50
times than the population of 1897 and cities like Dhaka, Kathmandu, Guwahati have
population exceeding several millions. It is a cause for great concern that the next greatearthquake may occur in this region at any time.
A strong earthquake affecting major urban centres like Dhaka, Chittagong, Sylhet
may result in damage and destruction of massive proportions and may have very severe longterm consequences for the entire country. After the 1971 independence, most major urban
centres of Bangladesh have grown tremendously due to unabated migration from the smaller
towns and rural areas. As a result, the cities have developed in haphazard fashion with little
consideration for proper town-planning norms. There is, consequently, a need to be preparedagainst all possible natural and man-made disasters that are likely to occur in Bangladesh. For
this purpose, it is essential to have realistic understanding of the consequences of likely
damage in major cities due to different disasters. This will permit rational planning of
mitigation efforts in order to minimise effects of these disasters.

65

Figure 1: Synopsis of historical and paleoseismic

Figure 2: Topographic map of the Ganges–Brahmaputra

history along the Himalayan Frontal Thrust (HFT)

Delta and Indo-Burman Fold belt showing GPS[after Berryman et al., 2014]velocities (after Steckler et al., 2016)

The extent of damage to structures and casualty level due to an earthquake in the
future can be reduced by the introduction of suitable mitigation measures. These mitigation
measures can be categorized as structural and/or non-structural. The structural measures arethose that directly influence the performance of building stock through strengthening of codeprovisions and the prevalent construction practice. Incorporating the appropriate structural
mitigation measures can reduce the vulnerability of any building type. The non-structural
mitigation measures include improvement in the state of awareness and preparedness before adisaster, land-use control and other government policies, and the infrastructure related toresponse following a disaster. The non-structural measures help to reduce the severity ofcasualty levels following an earthquake. In order to reduce the consequences of a major
earthquake in the cities of Bangladesh, it is necessary that appropriate structural as well as
non-structural measures be undertaken.
In this paper a brief summary of the activities and researches undertaken in the fieldof earthquake engineering in Bangladesh for the last six years have been presented. In an
earlier publication, similar activities for two decades (1993-2013) have been published(Ansary, 2014).

2. BANGLADESH UNIVERSITY OF ENGINEERING & TECHNOLOGY (BUET)
Department of Civil Engineering, BUET offers postgraduate courses on Earthquake
Engineering, Soil Dynamics, Structural Dynamics and Vibration Analysis. Until 1996, their66

existed only two postgraduate theses linked with Earthquake Engineering. But after 1996, atleast thirty more postgraduate theses related to this field were completed. Currently five
students are pursuing their PhD and several more students are pursuing for their Master’s
thesis in the Department in Earthquake Engineering field. BUET has also undertaken
research jointly with different local industry in the field of Geotechnical-Earthquake andStructural-Earthquake engineering fields (see Figures 3 and 4).
Recently, BUET with the help of Japanese government also established a new
institute on Disaster Prevention and Urban Safety, named BUET-JIDPUS (see Figure 5).
3. GOVERNMENT AGENCIES
Disaster Management Bureau (DMB) was established with the help of UNDP and UNICEF
in 1993. Although initially it was established to manage flood and cyclone, after the 1997
earthquakes in Chittagong and Sylhet region, Bureau started to train different government
officials and volunteers about pre and post-earthquake preparedness and management
techniques. For the last couple of years, Bureau conducted fifty or more earthquake training
workshops in different regions of Bangladesh. In 2002, it also published a Disaster
Management Training Manual. The second part of the manual has a complete chapter on
Earthquake Training Module and Public Awareness Guidelines. Recently, under the Disaster
Management Act 2012, DMB and DRR were merged to form a new Directorate called
Department of Disaster Management (DDM).

Figure 3: Shaketable test on sloped geotextile

Figure 4: Prototype models of Bangladeshi RCC structuresusing Sylhet sandto be tested on shaketable

67

Figure 5: Floor plans and outside view of BUET-JIDPUS

The Ministry of Disaster Management & Relief (MoDMR) is currently working as thegovernment coordinator for all activities regarding earthquake. Recently, they asked all theconcerned ministries, departments and armed forces division to submit Contingency Plan
regarding earthquake. The Ministry also compiled a list of available rescue and recovery
equipment available in the country. Some recent publications, activities of the MoDMR andother government agencies are shown in Figures 6 to 12.

68Figure 6: NPDM, Revised SoD and DM Act published by MoDMR

2015
Figure 7: Proposed seismic zoning

Figure 8: Vulnerability atlas for six cities of Bangladesh

map of Bangladesh69

Figure 9: Awareness raising rally and posters

CDMP Phase II (2010–14) builds upon and expands Phase I achievements by ensuringthat the institutionalization of risk reduction and climate change adaptation occurs across alllevels of government. The main tasks are:Task-I : Seismic risk and damage assessments and subsequent development of scenario-based
contingency planning for Rangpur, Dinajpur, Mymensingh, Tangail, Bogra, and Rajshahi
municipalities/city corporations of Bangladesh
TaskII: Development of detailed building and infrastructures database of Dhaka andChittagong City corporation areas

Figure 10: Training of urban

Figure 11: Training of masons and bar

Figure 12: Youth Campaign

volunteers

binders

for earthquake preparedness70Task-III: Development of Ward level Spatial Contingency Plans for Dhaka, Chittagong and
Sylhet City Corporation Areas in Bangladesh. The purpose of the plan is•To support with immediate local response initiatives to save maximum number of lives incase of an earthquake emergency in the particular ward, with a goal of stabilizing the event
within the first 72 hours.
Recently PWD completed a project funded by JICA. The overall goals are:
1. Retrofitting of public buildings including government building, hospital, fire station,school, shelter, etc. has been implemented. A retrofitted Fire Station at Tejgaon isshown in Figure 13.
2. Ministry of Housing and Public Works issues official license to the engineers uponcompletion of the training program introduced by the Project.
3. Manuals and the concepts prepared through the Project are incorporated in future
edition of Bangladesh National Building Code (see Figure 14).

The “Urban Building Safety Project” is a US$ 116 million investment, US$ 100 million
financed by JICA and US$ 16 million by the Government of Bangladesh. The project aims tostrengthen the building safety in Urban Cities by financing loans for building safety for
private buildings through Participating Financial Institutions (PFI), and by improving thebuilding safety for public buildings, thereby contributing to improvement of the social
vulnerability of urban cities. Under this project, one new fire service headquarter building(see Figure 15) will be constructed, ten FSCD stations will be retrofitted and several RMG
factories will get fund for retrofitting purposes.
The “Urban Resilience Project” is a US$ 179.5 million investment, US$ 173 million
financed by the World Bank and US$ 6.5 million by the Government of Bangladesh. The
project aims to strengthen the capacity of Government of Bangladesh agencies to respond to
emergency events and to strengthen systems to reduce the vulnerability of future building
construction to disasters in Dhaka and Sylhet. The above two projects have been jointly
launched by the Government of Bangladesh, JICA and WB on December 19, 2015.
Under the WB project, GEODASH (supported by Geonode) has been developed which isa Platform for Sharing of Earthquake Hazard and Vulnerability Data (see Figure 16).

71

Figure 13: Tejgaon fire station before and after retrofitting

Figure 14: PWD published manuals

Figure 15: Proposed new FSCD Headquarter with base isolation technology funded by JICA

72

Figure 16: Geonode, a WB supported data sharing platform also used in Haiti damage assessment

Proposed Bangladesh Urban Resilience Project of WB: City-level actors are critical to theeffort to develop resilient and livable cities in Bangladesh. This project seeks to create anenabling environment for coordinated, locally managed DRM. There are three core pillars of
disaster resilience in urban settings, including: i) effective emergency management; ii)
improving structural resilience through reduction of existing physical vulnerability; and risk
sensitive land use planning and safe construction standards and practices to ensuresustainable growth.
A comprehensive approach to increasing urban resilience requires coordinated long-term
investment across the three pillars. The Bangladesh Urban Resilience Project (BURP) would
serve as the first in a series of interventions, which will initially focus on Pillar 1, to improvethe critical capacity and infrastructure for emergency planning and response. The proposed
project will also lay the foundations for subsequent investments in Pillars 2 and 3 byidentifying key risks in the built environment and developing the practice of risk sensitive
urban development.
With the key elements of effective urban response in place, future attention could thenshift to reversing the trend of risk accumulation, and to increasing physical resilience throughbroader investments in priority sectors. Under this strategy, a second project would seek tofurther improve construction standards for future developments and reduce the existing
physical vulnerabilities in Dhaka and major cities across Bangladesh. A third project could
consider broader investment in priority sectors, for example critical facilities, water system,
power system, transport, and construction of protective infrastructure.

The BURP consists of four main components that focus on emergency response andpreparedness, establish an understanding of risk for critical facilities and essential facilities,
support improvements in urban development and construction, and provide the institutionalarrangements for implementation, monitoring and evaluation to ensure efficiency,transparency, and accountability in the implementation of project activities.
Component A: Reinforcing the Country’s Emergency Management Response Capacity.
There are several elements under Component A as follows:•

Creation of National Coordination Center and National Disaster Management Research
and Training Center that will operationalize and sustain a program for well-coordinatedemergency planning and response operations, and undertaken training, educational andawareness activities.

•

Enhancement of the emergency management planning and response capability of the Fire
Services and Civil Defense•

Building the emergency management capability along with establishing EoCs of the
Dhaka City Corporations and Sylhet City Corporation (see Figure 17)

Figure 17: Examples of EoCs

Component B: Program on Assessment of Vulnerability of Critical and Essential Facilities.
There are several elements under Component B as follows:•

Assessment of Vulnerability of Critical and Essential Facilities and Lifelines•

Data Sharing Platform to Support Risk-Sensitive Development

Component C: Improved construction, urban planning, and development. There are several
elements under Component C as follows:•

Creation and Strengthening of URU•Electronic Construction Permitting•

Professional Accreditation Program•

Building Code Enforcement

Component D: Project Implementation, Monitoring, and Evaluation.
In view of the recent earthquake trend in Southeast Asia, Directorate General of
Health Services (DGHS), Government of the People’s Republic of Bangladesh, has
undertaken an assessment to gain better understanding of the existing non-structuralvulnerability of hospitals at upazila and district level in order for making the hospitals seismic
resilient. Findings and recommendations from the assessment are believed to support DGHS
to plan and stimulate efforts to reducing non-structural vulnerability to earthquake so that thehospitals continue to function and contribute to response and recovery process after an eventof earthquake.
The assessment involved physical inspection of non-structural components of
hospitals. The work is done on 15 hospitals (5 district hospitals and 10 upazila healthcomplex) in the northern part of Bangladesh spread over active seismic Zone-One. Much
importance provided in the selection of district and upazila hospitals to maximize
representation of active seismic zone-one. The hospitals are located in Moulvibazar,
Sunamganj, Lalmonirhat, Kurigram and Sherpur district. Depending upon the capacity, there
are four types of hospital: 31 bed, 50 bed, 100 bed and 250 bed. The buildings of thehospitals are mostly RCC. A team comprised of six well trained data collectors dividing into
three groups carried out the inspection of non-structural elements during 24 April – 15 May
2016.
4. NON-GOVERNMENT AGENCIESIn 2011-2012 fiscal years, six International NGOs (Action Aid, Concern Universal, Concern
Worldwide, Islamic Relief Worldwide, Oxfam GB and Plan Bangladesh) represents
consortium on disaster management called National Alliance for Risk Reduction andResponse Initiatives (NARRI), Bangladesh and BNUS agreed to work on the following
issues:

Training module and resource material on Earthquake resistant construction
developed for the training ofo Civil engineerso Architect75

o Masons and bar binders

30 number of civil engineers, 20 numbers of architects, 75 numbers of masons / barbinders are trained on earthquake resistant construction



01 number of shake table demonstration on February, 2012 at Dhaka followed byopen discussion facilitated by relevant prominent experts in pre-identified schools,
markets, high rise building etc.



Structural safety (in view of Earthquake) assessment of 20 number of selectedbuildings are carried out with a concise report highlighting recommendations



Review of existing Bangladesh National Building Code in view of Earthquake safety
is conducted along with recommendations and documented Advocacy material andIEC on building codes are developed targeting general community residing in urban
settings, Engineers / Architect, builders and policy makers



02 number of advocacy workshops / seminars are organised to advocate and promote
at both Dhaka and Sylhet levelo Enforcement of improved building codes / bylaws in view of Earthquake
safetyo Required changes in existing syllabus of undergraduate courses in civilengineering and architecture in view of seismic safe constructiono Certification of engineers / architect and masons / bar binders trained onseismic safe construction \o Establishmentofappropriate

institutionalarrangementtomonitor

implementation of building codes.
Under this project, A Manual for Architects, A Manual for Engineers, A Manual for Masons
was developed. Also structural assessment of some selected schools of Sylhet city was
carried out.
5. DISASTER MITIGATION IN BANGLADESH
Bangladesh achieved remarkable success in managing frequently occurring hazards such as
cyclones and floods. The country has a well-organized Cyclone Preparedness Plan (CPP),
which boasts a volunteer list of around 44000. Even country like India and Sri-Lanka try toemulate CPP. To cope with the earthquake disaster a similar Earthquake Preparedness Plan
(EPP) need to be implemented. Currently FSCD started training 62000 urban volunteers toenrich EPP.
76

For earthquake disaster mitigation professional as well as government solution isrequired. Architects, engineers, geologists, planners etc. will provide technical aspects andNGOs, mass media and social scientists will provide social aspects of professional solution.
Builders, financial institutions, land developer would be required to support professional
solution. Government agencies can help to implement professional solution throughpolicymaking and policy enforcement. Government solution should clearly point out
regulatory jurisdiction of each organization. For earthquake disaster mitigation following preand post measures should be undertaken on an urgent basis.
Awareness and capacity building

Increase public awareness through education (school children), earthquake drills,
interactive website, mass-media, publication, training etc.

Training of building inspectors, community leaders, construction workers andmasons.



Updating earthquake engineering course curriculum.

Earthquake engineering researchInstallation of free field accelerographs and seismographs for engineering andseismology studies.



Seismic hazard assessment based on free field data and source models.



Vulnerability assessments of structures using structural analysis and nondestructive
testing.

Develop laboratory and testing facilities.



Development of indigenous and cheap retrofitting measures. Microzonation of urban
areas based on different soil effects.

Updating building code.

Earthquake resistant constructionLegal enforcement of building code.

Proper use of ductile steel and lateral force resisting systems.



Building insurance to promote earthquake resistant construction.

77

Retrofitting critical structures such as schools, hospitals and fire offices.



Urban and regional planning to mitigate earthquake effects.

Post-earthquake response

Develop automatic safety shutdown system for electricity, gas, telephone and watersupply system whenever the ground shaking exceeds a certain limit.



Develop facilities for post earthquake search and rescue operation.



Local people and organizations most effectively do rescue of victims because they areable to carry this out more quickly than outside agencies. Community based voluntarygroup should be trained who can actively participate in rescue operation just after anearthquake disaster.

Prepare contingency plans.



Coordination among different interest groups those will be involved in the post
earthquake rescue effort.



Arrangement of emergency medical treatment facilities for injured people.

REFERENCES
Ansary, M.A., 2014. Earthquake Related Research and Activities in Bangladesh during thelast two decades, published by BSRM in June, 2014.
Berryman, K., W. Ries, N. Litchfield, 2014. The Himalayan Frontal Thrust: Attributes forseismic hazard, Report produced in the context of the GEM Faulted Earth Project.
Sinha, R. and Goyal, A., 1994. Damage to buildings in Latur earthquake, Current Science 67,
380-385.
Steckler, M., Dhiman Ranjan Mondal, Syed Humayun Akhter, Leonardo Seeber, Lujia Feng,
Jonathan Gale, Emma M. Hill and Michael Howe 2016. Locked and loading megathrust linked to active subduction beneath the Indo-Burman Ranges, Nature Geoscience· July 2016.

78

PART-VIII

USE OF JET GROUTING IN
RETROFITTING OF A RMG FACTORYBUILDING IN CHITTAGONG,
BANGLADESHBANGLADESH NETWORK OFFICE FORURBAN SAFETY (BNUS), BUET, DHAKA

Prepared By: Mehedi Ahmed Ansary79INTRODUCTION
The retrofit process is a general term that consists of a variety of treatments, including:preservation, rehabilitation, restoration and reconstruction (Kelley, 1996). When an existingbuilding found potential for severe damage due to lack of capacity against various possible
loading, is considered for retrofitting. Most of the structures built prior to 2000s in
Bangladesh were typically not designed with proper details to perform adequately during
earthquakes. While Details Engineering Assessment (DEA) conducted in several buildings,
most of them have been found vulnerable against seismic load. Recent events like collapse ofRana Plaza in Bangladesh have increased the awareness among building owners as well asbuilding users for various purposes. The seismic retrofitting design and construction haverecently been initiated in Bangladesh for vulnerable buildings. In retrofitting, strengtheningof all structural elements has been considered as per requirements and relevant deficiencies.
Jet grouting columns are frequently adopted in foundation engineering as an alternative topiles with the aim of strengthening weak subsoil and transferring loads to deeper and morecompetent strata (Modoni et al, 2010). Jet grouting, among all kind of soil improvement, has
certainly acquired a special place due to its widespread use in all kind of soil and capabilityof giving convenient solutions to most geotechnical problems. Jet grouting technology cangive practical and cost-effective solutions to a number of difficult situations, such as for
excavation support, ground-water barrier, bottom sealing to prevent pollutants from entering
excavations, protection of bridges against scour, stabilization of slopes and underpinning ofexisting foundations in commercial and industrial settings (Croce et al., 2014). It is
commonly recognized that jet grout was first applied to soils by the Japanese in 1960’s(Nakanishi 1974).The experience on the use of high-speed jets in late 1960s for cutting rockand rock-like materials (Farmer and Attewell, 1965) inspired a group of Japanese specialists
to investigate their use as a ground improvement tool. They developed an idea of injecting
fluid binders within previously drilled boreholes to erode and mix in place the soil. Chemicalbinders were used in the first patented version, known as the Chemical Churning Pile (CCP)(Miki 1973; Nakanishi 1974), but these products were soon replaced by water-cement grouts.
In the subsequent decades, the technique has developed significantly and is now being widelyused around the world. The CCP and Jet Grout methods came to the attention of European
companies in general and Italian companies in particular on the occasion of the international
competition on the methods for the stabilization of the Pisa Tower in the early 1970s (Croce
et al., 2014).Currently, jet grouting is used all over the world (Ryjeski et al. 2009).

80

This paper presents the first ever use of Jet Grout in Bangladesh for retrofitting of an existing
foundation of a four storied RMG building, situated in Chittagong Export Processing Zone,
Bangladesh. Figure 1 shows the building before and after retrofitting. The building is a RC
beam-column structural frame system and the structural configuration is regular in pattern.
This building has been constructed in 2001. A DEA has recently been carried out by EIMS
to ensure the serviceability of the building. After completion of the DEA, the building has
been found structurally inadequate due to highly stressed conditions of several columns andexisting mat foundation considering existing gravity and lateral loads as per Bangladesh
National Building Code (HBRI, 1993).The report suggested preparing retrofitting design andconstruction of the building to sustain lateral load as per BNBC. When it comes to retrofitting
design, preparing a constructible design is the main challenge for structural engineers due toits existing condition. Considering all difficulties of construction, column jacketing andconcrete shear wall scheme have been proposed to give the super structure an overall stability
against all kind of possible loading. To overcome the foundation inadequacy deep beams
have been inserted in two opposite side of the mat resting on Jet Grout Columns (JGC).
While constructing the JGCs, there are several obstacles due to existing condition. The sizesof the JGCs have been adjusted as per field condition. Full control of jet grouting application
has been maintained by monitoring all jet grouting phases carefully. The diameter of the pilehas been checked by digging up to a depth of several feet for most cases. The core sample has
been collected from grout piles and compressive strength has been evaluated. Subsoil
investigation and Static Pile load test have also been carried out.
In this paper methodology of retrofitting design for both super and sub-structure is discussed
along with the changes that have been made due to field condition. Construction process,
impediments and relevant changes are also included. In addition, type of treatment,
application procedure and operational parameters for jet grouting are discussed.

81

(a)
(b)
Figure 1: Building (a) before and (b) after retrofitting

BUILDING INFORMATION AND DEFICIENCES
The evaluated building is a four-storied concrete moment resisting frame. The structuralconfiguration of this building is regular in pattern. All of the interior columns are circularhaving 650mm in diameter and all edge and corner columns are square in shape having
500mm x 500mm in size. Typical floor beams are 250mmx700mm in size along bothprinciple directions of the building. Crushed stone chips have been used as coarse aggregate
for concrete and steel deformed bars have used as reinforcement. The ground floor height is
5.55m and other typical floor height is 3.6m. The existing floor system is a two way edge
beam supported floor having 160 mm thickness. The plan dimension of the building is
21.4mx21.4m. The existing foundation is mat foundation having a thickness of 500mm. The
ground floor is a structural floor with proper reinforcement and thickness is 200mm. The
evaluated concrete strength as per ACI 562 (2013) is 18.4MPa and the yield strength of
deformed bar is 420MPa. The main use of the building is to supply electricity to othersbuildings. There are several high voltage generators and other machineries related toelectrical connections and supply in the ground floor. The other floors are used for officepurposes and the top floor for garments product.
Based on DEA, several structural deficiencies have been identified. Most of the columns are
inadequate in capacity due to earthquake forces. The reinforcements of mat foundation along
both principle directions is inadequate for bending moments due to upward soil pressurecaused by the action of gravity loads. The underneath soil of the existing mat foundation isfound to be compacted. The estimated settlement is acceptable.

82

SEISMIC RETROFITTING DESIGN AND CONSTRUCTION
Since the structural elements are mainly inadequate due to lateral forces and the access forstrengthening the interior columns are not possible due to existing condition, additional
concrete shear walls are attached to the exterior columns at front and rear sides of thebuilding. From numerical analysis, it has been observed that shear wall increased overalllateral stiffness of the building, also the inter-storey drift of the first floor remains withintolerable limit. Along with shear wall, two columns are also strengthened as per conventional
column jacketing procedure using high strength concrete. Concrete shear wall required deep
foundation to resist the uplift force action due to lateral forces. For this purpose cast-in-situ
piles in addition have been considered below the foundation of the shear walls.
Inadequacy of the foundation occurs due to upward soil pressure that reacts against thevertical loading of the building. To rectify this inadequacy reinforcement of top layer need to
be increased in both principle directions. This is practically impossible due to the setup ofelectric generator at the ground floor and presence of active electric lines under the groundfloor slab. The designer has proposed to let the mat distribute its load in such a way that it
will reduce soil pressure on it. Mat connecting deep beams (thicker than the normal beam)
have been proposed along the front and rear sides of the building. These two deep beams
have been connected with the mat. The mat behaves like a two way edge supported slab andthe moment due to upward pressure of underneath soil will be transferred by the deep beams.
The compacted soil is not fully capable to support the beams. Therefore continuous cement
grout columns (JGC) are considered. These JGCs will be able to reduce the deflection of deep
beams. Figure 2 shows the location of JGCs.
The retrofitting construction has been completed within three months. Within this time
period, forty six Jet Grout columns (JGC), sixteen bored piles, two 21m long mat connecting
deep beams, eight pile caps, six mat beams, two column jacketing and eight shear walls havebeen constructed. Figure 3 shows construction of different new building elements for
retrofitting purposes.

83Front Side of the Building

Back Side of the Building
Figure 2: Designed location of Jet Grout Columns

Reinforcement Arrangement for Deep Beam

Reinforcement Arrangement for Deep
Beam and Pile Cap

Reinforcement Arrangement for Shear wall

Reinforcement Arrangement for Column
JacketingFigure 3: Retrofitting of different elements of the building

JET GROUTING SCHEME
Jet Grouting is adopted as the measure for soil improvement for this project to overcome thefoundation deficiencies. A drill rig advances the jet grout monitor to the bottom of theproposed treatment zone at which high velocity injection of fluids (often sheathed in air) are
initiated as the monitor is slowly rotated and lifted. The jet erode and flush out a portion of
the in situ soil and mix the remaining soil with cement grout to form a mass of stabilized soil,
referred to as jet grouted soil (Sweeney et al., 2001). Currently, there are three major forms ofjet grouting which involve the injection of a single fluid, two fluid or three fluids(Kauschinger and Welsh, 1989). Double fluid system has been used in the present case.
1. Selection of Jet Grout for this Project
The major concern of the project is laying the deep beam in a base with sufficient bearing
capacity or transfers the load to other load bearing elastic foundation. The soil needs to betreated to increase its bearing capacity having settlement within tolerable limit. Otherwise
install a deep foundation under the beam. The deep beams to be constructed are adjacent tothe building and the working space is congested. In this working space, installation of a deep
foundation is almost impossible. Due to this reason, improving the soil improvement through
JGC is the only viable solution. JGC is the most viable solution due to its capability to create
large columns of cemented material by drilling small holes into the ground, with limited
disturbance of the surrounding subsoil. Moreover jet grouting is an erosion-based process,and subsequently can be effective across the widest soil spectrum (Burke and Sehn, 2003).
With a number of jet grouted column in a row will provide a level platform which will
prevent any detrimental settlement. For the above reasons jet grout columns have been
selected for this project.

2. Design Methodology
In designing jet grout, the first thing is to decide how much of soil need to be improved toattain the desirable soil properties. Based on that designer decides the volume of jet grout tobe done and the arrangement of jet grout columns as per volume requirement. Design
process, strictly related to the quantification of the technological effects: the choice of the jet
grouting procedure, the quantification of treatment parameters, the prediction of thedimensions and the mechanical properties of the jet grouted piles and the analyses of possible
undesired collateral effects on the surrounding constructions and on the environment. In thisproject, the main purpose of jet grout column is to transfer loads to deeper and morecompetent subsoil strata, bypassing weaker or more deformable soils. Also to prevent any
detrimental settlement to provide the deep beam an elastic base foundation. The design of jet

85grout column is done as per subsoil condition as shown in Figure 4. The soil report showsthat the soil is mainly silty fine sand up to a depth of 24.4m except from 7.62m to 10.67m,
the soil is soft clayey silt. The capacity (tip resistance and skin friction) of a single JGC has
been estimated based on the available data which is obtained from the subsoil investigation
report.

Figure 4: Subsoil report at the project site
As per site condition, three different diameter of grout columns have been selected, they are
800mm, 600mm and 500mm Due to lack of access in some locations, higher diametercolumns have been used as the spacing is higher. Also when the spacing is less, the smaller
diameter has been used. The length of the designed column is 18.3m. For this project site, theestimated column capacity for 600mm diameter is 300kN, for 500mm diameter the estimatedcolumn capacity is 235 kN and for 800mm diameter the estimated column capacity is 500
kN. This has later been verified by static pile load test (ASTM 1143, 1994) for the for
600mm diameter column. Jet grout strength is primarily determined by the soil type; however
the amount of cement used per unit volume and the water-cement ratio also has an effect. In
design, the compressive/bearing strength of the soil is assumed to be 3000kN/m2, which isalso verified by collecting cores from the JGCs constructed at the site. The grout mix iscomposed of water and cement dosed according to weight ratios (W/C), usually ranging

86

between 0.6 and 1.3. Selection of these parameters is very important for achieving design
strength. In this project, the selected the water and cement is 1:1.
3. Construction Methodology
Jet grout columns are installed by initially drilling a small hole, typically 100 mm in diameterto the required depth. In the double fluid system, the grout is encased within a shroud ofcompressed air. The air acts as a buffer between the groundwater and the grout, greatly
increasing the cutting efficiency. It also creates turbulence in the waste spoil, improving theefficiency of its removal. In this method a special coaxial drill string and jet monitor has beenused. The cutting jets are located above the grout supply, which allows a nearly complete
replacement of the soil with grout as the monitor is withdrawn. The double fluid jet grouting
system used for this project is shown in Figure 5. Double fluid jet grouting is typicallyconstructed from the bottom upwards. Column size is dependent on parameters such as
rotation rate, lift rate, injection pressure and grout flow rate. Selection and control of theseparameters are the main task in construction stage to attain desirable results for the structure.
4. Application procedure
In construction of the project, all necessary machinery for jet grouting needs to be placed in aconvenient way to facilitate the work condition. For jet grouting pump machine a temporary
work station has been selected. The air compressor as shown in Figure 5 (c) has been placednear the work station. Near this place the mixing plant for grout has also been set. The
drilling rig has been positioned on top of two pipes so that the machine can easily be moved
to its desired point. In this project, jet grouting pile installation process has been executedwith the help of four operators. A supervisor has also been involved to take care of the grout
mixing. After finishing one jet grout column, the machine has been shifted to the alternative
point of jet grout column, skipping the adjacent pile. This way time is given to newly
installed pile to be cured, at the same time maintaining the time schedule.

5. Type of Treatment
The soil beneath the deep beam needs to be treated. The deep beam is about 600mm in widthand length of around 21m. The soil beneath the beam needs to be improved for an area of
21m long strip with a width of 600mm. In that case, a series of jet grouted pile needs to beinstalled in a single row along the strip having a diameter of around 600mm as shown in
Figure 2. As per design, to transfer the imposed load to a hard stratum, JGCs has been formed87

up to a depth of 18.3m. It has been observed that during actual construction some of the JGCs
can’t be placed according to the design as shown in Figure 2 due to existing pipes and otherinstallations. For this reasons, the diameter of some of the JGCs have been increased or
decreased as per requirement so that the overall objective of grouting may be fulfilled (asdiscussed in design methodology).

(a) Grouting
Machine(C)
Air
Compression
System(b) High Pressure Jet Grout Pump System
Figure 5: Jet Grout Column Construction on site

6. Operational parameter
In JGC construction, the operational parameters are injection pressure, number and diameterof nozzles, rotation and lifting speed of the rods and flow rates. These parameters have been
set according to appropriate calculation and as a result of required diameter according to thedesign. Following factors may affect the selection of operational parameter: subsoil
condition, desire pile diameter, desire jet grouted soil bearing capacity, applied jet grouting
technique. For this project, operational parameter has been determined by a field trial. The
operational parameters used in this project are presented in Table 1.
Table 1: Operational Parameters of JGC construction at the project

Operational Parameter

Unit

Value for different diameter, D of Jet
Grout Column
D=800mm

D= 600mm

D= 500mm

Injection Pressure

MPa

20~35

20~35

20~35

Number of Nozzles

No

2

2

2

Diameter of Nozzles

Mm

1.8

1.8

1.8

Rotational Speed

Rpm

20

20

20

Lifting Speed

cm/min15

20

25

Flow rate

Liters/min

5.25

2.65

1.81

88

7. Performance
As the project is the first project for the designer and the contractor, the result of theirassumption need to be verified by field trials. The first thing is to check the diameter of thegrout piles. The diameter is physically checked by excavating the JGC heads. It has beenfound that the diameters are okay as per design requirements. Figure 7 shows one of the
excavated areas to find out grout pile diameter and the process of core collection. The
compressive strength has been ascertained for eight collected core samples. Table 2 shows
the core test results.
Table 2: Crushing Strengthof Jet Grout Core
Sl
No

Crushing
Grout
Strength
Pile
Diameter (MPa)

1

800mm

3.6

2

800mm

1.4

Figure 6: Exposed (a) JGC and (b) Sample Core
Collection

3

600mm

2.6

The average compressive strength of all the cores is 2700

4

600mm

2.6

5

500mm

3.1

6

500mm

2.7

(b)

(a)

2

2

kN/m , slightly lower than the design value of 3000 kN/m

Static pile load test on a test JGC of diameter 600mm has
also been carried out as per ASTM 1143 (1994) up to failureof the pile. The pile load test setup is shown in Figure 7.

(a)

(b)

Figure 7: (a) Static Loading System on top of a JGC and (b) Hydraulic Jack anddial gage setup

89

The load versus settlement curve for the tested JGC is shown in Figure 8. The ultimate
capacity of the tested JGC is approximately 1000 kN. For a factor safety of 2, the allowablecapacity is 500kN which satisfies the designed value of 300 kN for 600mm diameter column.

Figure 8: Load versus settlement curve
CONCLUSIONSFoundation bearing improvement of a four-storied RMG factory in Chittagong is one of thefirst applications of Jet Grout Column in Bangladesh. As a result of this soil improvement,
the predicted settlement under the existing raft will be low as well as the raft will be able tocarry additional loads coming from the new shear walls inserted on the superstructure. The
high speed of jet grouting application allowed the other construction phases take place
immediately such as lean concrete works, drainage, deep beams, new shear walls etc. The
appropriate selection of the operational parameters resulted in a successful treatment that has
been proved by technical methods such as trial excavations, core sampling and static pile load
tests.
REFERENCESACI (American Concrete Institute) Committee 562. (2013) Code Requirements for
Evaluation, Repair, and Rehabilitation of Concrete Buildings (ACI 562-13) andCommentary, ISBN: 9780870318085
ASTM (American Society for Testing Material) Designation D 1143//D 1143M – 07 (1994).
“Standard Test Method for Piles under Static Axial Compressive Load”.

90

Burke, G.K. and Sehn, A.L. (2003). “The influence of ground improvement on geotechnicaldesign”. ASCE/PENNDOT 20th Central PA Geotechnical Conference, October 29-31,
2003.
Croce, P., Flora, A., Modoni, G., (2014). “Jet Grouting Technology, Design and Control”
CRC
Press, ISBN 9780415526401 - CAT# Y136059
Farmer, W. and Attewell, P. B. (1965). “Rock penetration by high-velocity jet”. International
Journal of Rock Mechanics and Mining Sciences 2: pp. 135–153.
HBRI-BSTI (1993). Bangladesh National Building Code.
Kauschinger, J. L. and Welsh, J. P. (1989). “Jet Grouting for Urban Construction,” Proc.,
Geotechnical Lecture Series, Boston Society of Civil Engineering: Design,
Construction, and Performance of Earth Support Systems, MIT, Cambridge, MA.
Kelley, S. J.(1996). “Standards for preservation and rehabilitation”, West Conshohocken, PA,
ASTM, 1996.
Modoni G., Bzòwka J., and Pieczyrak, J. (2010). “Experimental investigations and numericalmodelling on the axial loading of jet grouting columns” Architecture Civil
Engineering Environment Journal (ACEE), Silesian University of Technology, ISSN
1899-0142 (code E201327)
Nakanishi, W. (1974). “Method for Forming an Underground Wall Comprising a Plurality ofColumns in the Earth and Soil Formation”, U.S. Patent 3,800,544: 8 p.
Ryjevski, M., Shramko, K., and Baghirova, E. (2009). “Jet grouting application forDubai
Metro Construction”, Proceedings of the World Tunnel Congress, Budapest, Hungary,May 23-28, 2009.
Sweeney, B.P., Wheeler, J.R., and Henry, L.B. (2001). “Design and Construction of a JetGrouted Excavation Support Wall in an Urban Environment.” Foundation and ground
Improvement, Proceeding of the conference, American Society of Civil Engineers.

91PART-IX

AMBIENT VIBRATION ANALYSIS OFHERITAGE UNREINFORCED MASONRYBUILDINGS IN BANGLADESHBANGLADESH NETWORK OFFICE FORURBAN SAFETY (BNUS), BUET, DHAKA

Prepared By: B.S.P. Biswas
Mehedi Ahmed Ansary

92

1.

Introduction

Bangladesh is located in a seismically moderately region in Global Seismic Map prepared by Global
Seismic Hazard Assessment Program (GSHAP, 1992). Although no major earthquakes occur in thiscountry in the last few decades. During the past few earthquakes and also in the time of recent
earthquakes, the masonry structure of Bangladesh shows poor structural behavior. Ancient masonry
structures are particularly less vulnerable to dynamic actions, especially seismic actions.
Unreinforced masonry was a very common practice and used technology. Those heritage unreinforced
masonry structures have been named according to their extent of Bengali civilization, cultures andreligions. Few of those are- Pala Buddhist architecture, Islamic and Mughul architecture, Terracotta
temple architecture, Common Bungalow style architecture, Indo-Saracenic revival architecture etc..
Later on the British colonial age predominantly represent the buildings of the Indo-European styledeveloped, which is mainly a mixture of Indian European and Central Asian components. The more
prominent works amongst them are Ahsan Manzil in Dhaka and Tajhat Palace in Rangpur City. All ofthem are mostly masonry, sometimes in combination with stones and other local materials [1].
The remains of the ancient archaeological sited bear ample testimony to the fact that are the art ofbuilding was practiced in Bengal from early period of her history. A satisfactory reconstruction of thehistory of architecture in ancient Bengal has been found from the evidence of the disappearedmaterials. The structures were rudimentary wattle and dub construction with beaten earth flooring.
The early period of the history has witnessed the spouting of a number of urban centers at sites like
Mahasthan at Bogra City in Bangladesh and in west Bengal at Bangarh at Dinajpur City,
Chandraketugarh at 24 Paraganas district, Mangalkot at Burdwan district, Pokharana and Dihar.
Traces of mud ramparts, noticed at several of these sites suggested that an early Bengal City often
contained an acropolis.
In addition mud, bamboo and timber and occasionally burnt bricks were used for building houses.
Terracotta drainpipes and ring wells were also found. But later after, during the succeeding periods,
represented by sites like Banarh and Mahasthan, the houses became more and more complex, with asimultaneous increase in the use of burnt bricks [2].
Mosque architecture (1205-1765) was introduced by the Muslims to ritual needs of their religion,
Islam after the establishment of Muslim rule in Bengal. For this consequence numerous mosque werebuilt during the five and a half centuries of the Muslim period before the British colonial period. Most
the building were constructed with burnt bricks and stones. Bricks an easily manufactured material
form the abundantly available clay of the delta, has been the traditional building material of Bengal
from the ancient times, as seen in the ruined but monumental Mainamati and Paharpur, monasteries in
Bangladesh.

93

Although rooted in the 15th century architectural traditions of Bengal, their stark, unadorned exteriors,circular engaged corner towers and massive appearance shows the considerable influence from
Tughluq architecture of Delhi. The most important of this approach is the Shatgumbad Mosque in
Bagerhat district of Bangladesh. The mosque has eleven bays and seven aisles, with the largest bay inthe center. This central bay is divided into seven independent, rectangular bays that are covered by thechau-chalas; this being the earliest use of the form in Bengal. The interiors of the miniature chauchalas have thin, raised bands of brick that imitate the rafters and purlins of bamboo hut frames. There
are seven entrances each on the north and south sides. It seems that the stone pillar once had brickcasings, because there are traces of brickwork around some of their bases.
The Chhota Sona Mosque in Gaur dated by inscription to the reign of sultan Alauddin Husain shah(1494-1519), and was built by a high official in the royal court. This rectangular mosque iscompletely faced with stone in the exterior, while inside there is stone up to the springing of arches.
Pillars, pilasters and the platform in the northwest corner are of stone. There is abundant stone craving
in low relief in the exterior and ornamental niches within rectangular panels, rosette and pot motifs
that are used repeatedly.
The Chatmohar mosque in Pabna district dated 989 AH (1581-82) and the Kherua mosque in Sherpur
district dated 989 AH (1582). These mosques used the single aisle, three bayed plan which was tobecome the paln par excellence for Mughal mosques in Bengal from the 17th century onwards. In
elevation the octagonal corner towers, the curved cornices. Low drum less domes, brick surface andpointed arches link them to the Sultanate style.
A refined Mughal provincial style was developed in the capital city Dhaka in the 17th century. The
Lalbagh Fort Mosque in Dhaka dated 1059 AH (1649) and 1194 AH (1780) conforms to the typicalMughal mosque plan which was mostly masonry [3]. Kantanagar Temple, commonly known as the
Kantaijiu Temple is a late-medieval Hindu temple in Dinajpur district of Bangladesh. The Kantajew
Temple is one of the most magnificent religious edifices belonging to the 18th century. The temple
was built by Maharaja Pran Nath, its construction started on 1704 CE and ended in the region of his
son Raja Ramnath on 1722 CE. It boasted one of the greatest example on terracotta architecture in
Bangladesh and once had nine spires, but all were destroyed during the great Indian Earthquake thatlook place on 1897 [4].
One of the most vulnerable forms of construction to damage in construction is unreinforced masonry.
The 1989 Newcastle, Australia, earthquake was a recent event that demonstrated this vulnerability.
The majority of damage in Newcastle was to older load bearing masonry construction or nonstructural
masonry. Also a large number of small and large masonry performed well during the earthquake [5].
Historical structures have been built without accounting for the seismic actions and are vulnerable
even to moderate events but, due to their historical importance and to the daily presence of tourists,94

their seismic rehabilitation is quite delicate, aiming at the protection of both human life and cultural
heritage. Seismic preservation should be based on a good knowledge of the dynamic characteristics ofthe structure and a suitable choice of the intervention, if necessary. The first step is very important inorder to assess, also by means of a suitable numerical model, the possible dynamic behavior of thestructure during strong events. But it is not easy for several reasons: the structural size of the various
elements (walls, floors, etc.) cannot be evaluated with the needed accuracy; the material
characteristics, such as the tension-strain relationship, the strength, etc., are not known; structure andmaterials often exhibit inelastic behavior; horizontal structures are not effective in joining the verticalones; the depth of the foundations is often variable as well as their geometry and material properties,
including the soil characteristics; buildings are often connected to other constructions, so that their
behavior is very complicated. For such kind of structures the experimental analysis is often the only
way to improve our understanding about their dynamic behavior [6, 7, 8, 9 & 10].

2.

Methodology

2.1 Study Design
Masonry is the building of structures from individual units laid in and bound together by mortar; theterm masonry can also refer to the units themselves. The common materials of masonry construction
are brick, building stone such as marble, granite, travertine, and limestone, cast stone, concrete block,glass block, and cob. Masonry is generally a highly durable form of construction. However, thematerials used, the quality of the mortar and workmanship, and the pattern in which the units areassembled can significantly affect the durability of the overall masonry construction.
This research was initiated to collect preliminary information for heritage unreinforced masonrybuildings in the Dhaka City. The purpose of conducting ambient vibration testing in general is toobtain the dynamic characteristics of a structure, its natural frequencies, corresponding mode shapes
and damping estimates. The structure is assumed to be excited by wind, traffic and human activity.
The measurements, typically accelerations, are taken for a long duration to ensure that all the modes
of interest are sufficiently excited. Microtremor measurements were carried out to characterize the site
dynamics. Five sensors were used for the measurement. The buildings are typically two storied withsome part three storied. Three sensors were placed at different three stories on the line of stiffness ofevery floor. Other two sensors were placed on the ground to record the soil dynamics.
The present state of knowledge concerning shear strength and shear load-displacement behavior ofmasonry is far less advanced than that concerning masonry behavior in compression, even though
shear failure is an important, often governing mode of failure in many masonry buildings [14]. This

lack of understanding is reflected by the low values of shear resistance allowed by present U.S.
building codes (ASCE 31 02). Information on the post-peak behavior and on the deformations95

associated with pre-peak and post-peak responses are also lacking. Only recently, the terms softening
and dilatancy were introduced in the research community [15]. Knowledge of such behavior is essential
if adequate analytical models are to be developed to describe the in-plane behavior of masonry walls.
Most of the research conducted to date regarding the masonry shear behavior has been limited todetermining the peak shear stress and affecting parameters.

Lime mortar was used as the bonding material in all the three study buildings. It was required to checkthe shear stress of the bonding mortar of masonry. Direct shear test has been carried out to find thebest result for mortar strength at one building (Old academic Building of BUET) as identical as all thethree buildings are similar in bonding material. This paper describes the buildings tested, the tests andresults, and the methodologies and equipment used.

Figure 1A: Dhaka City Map (source: Dhaka Map Figure 1B: Location of Study Area (source:of RAJUK website)

Google map)

2.2 Study Area Selection
The tests were performed on and around three buildings of Dhaka City. Figure 1A shows the map of
Dhaka City and figure 1B shows the locations of the three buildings tested in the Dhaka City. The
buildings were the Curzon Hall Musa Khan Mosque Building, shown as Point A, the Aambour ShahShahi Mosque, shown as Point B, and the Old Academic Building of Bangladesh University ofEngineering and Technology (BUET), shown as Point C. The points were taken for the microtremor
measurements. The three buildings feature similar structural systems, with unreinforced masonry load
bearing walls at the sides of the buildings with a mix combination of wood and I-Joist steel diaphragm
floors connecting them.

2.3 Description of Buildings
2.3.1 Musa Khan Mosque at Curzon HallThis mosque is located at Curzon hall in Dhaka University at latitude 23°43'38.5"N and longitude
90°24'06.9"E. The Musa khan mosque (Figure 2) belongs to oblong shaped plan measuring 15.17 m
by 7.54 m externally with a 1.52 m thick surrounding brick wall. The prayer hall is entered from theeastern side by three archways and the other two side walls have one pointed-arch openings each. To
articulate the main mihrab niche from outside, the kibla wall is projected in the centre towards thewest. The whole length of the rectangular hall is divided into three unequal bays by means of two 1.06
m wide arches springing from the east and west walls. The side bays are rectangular in shape andsmaller in width, but the central one is bigger and square. With the help of brick pendentives thesquare central bay is transformed into an octagonal area. By introducing a series of sequences theoctagonal area is transformed into a circular supporting area, upon which the dome supports. The two
smaller rectangular side bays are converted into square supporting areas for the dome by using two
half domed vault springing from the eastern and western walls. Plan and front elevation of the mosque
are shown in Figure 3 and Figure 4 respectively.

972.3.2 Aambour Shah Shahi Mosque at Karwanbazar
One of the most well preserved mosque complex of Dhaka city belonging to the 17th century is the
Aambour Shah Shahi Mosque (Figure 5). It is located at Karwran bazaar in Dhaka City at latitude
23°45'11.6"N and longitude 90°23'35.0"E). The mosque proper has the usual oblong shaped planmeasuring 13.41m by 7.30m externally with a 1.2m thick along east-west direction and 1.6m thickalong north-south direction brick wall. The prayer hall is entered from the eastern side by threearchways and the other two side walls have also one arch opening each. Corresponding to the threefrontal openings, the kibla wall is niched with three mihrabs. The rectangular shaped prayer room isdivided into three square bays by two wide transverse corbelled cusped arches supported by twin
brick pilasters embedded in the east and west walls. With the help of half domed squinch at eachcorner, each square area is transformed into a circular supporting area, upon which the dome supports.
All the three domes, with a very low shouldered dome on a cylindrical drum, are crowned with lotus
and kalasa finial. The central one is slightly higher than the flanking ones. Plan and front elevation of
the mosque are shown in Figure 6 and Figure 7 respectively.

2.3.3 Old Academic Building (OAB) of BUETThe Old Academic Building of Bangladesh University of Engineering and Technology (BUET) atlatitude 23°43'39.0"N and longitude 90°23'34.2"E was built on the early 1900’s (Figure 8).Some partsof the building is two stories and some parts is three storied. The OAB building has a mixed used of
office cum academic. The OAB’s proper has plan measuring 70.5m by 48m externally with a 1.1m
thick brick wall every direction. It is Unreinforced Masonry Bearing Walls with Stiff Diaphragms(Building Type 15 according to ASCE/SEI 31-03) [13]. First floor (2nd story) is slab supported onmasonry wall, Ground floor (1st story) is slab on grade. It is mainly unreinforced burnt clay brickmasonry with lime mortar. Plan of the OAB is shown in Figure 9.

98

1.3m

1.07m

1.9m

4.5m

1.2m

1.9m

7.54m

1.5m
1.83m

1.83m

1.83m

0.83m

Figure 3: Plan of Musa Khan Mosque

Figure 2: Musa Khan Mosque

Figure 4: Front Elevation of Musa Khan Mosque
13.41m
0.84m

1.3m
1.2m

2.5m

4m

2.5m

1.2m

7.3m

1.6m
1.2m

1.8m

1.2m

Figure 6: Plan of Aambour Shah Shahi Mosque

5 .5 m

2 .9 m
2 .3 mFigure 5: Aambour Shah Shahi Mosque

Figure 8: Old Academic Building of BUET

2 .3 mFigure 7: Front Elevation of Aambour Shah Shahi Mosque

Figure 9: Plan of Old Academic Building99

2.4 Data Collection Using Microtremor
The purpose of conducting Microtremor measurements is to obtain an estimation of site response for aparticular location. Three approaches are commonly used to analyze microtremor data; power spectral
densities obtained directly from the Fourier amplitudes, spectral ratios relative to a reference site, andNakamura’s technique [12], which is defined as the spectral ratio of horizontal components to verticalcomponents recorded at the same site (H/V ratio). It is common to perform tests over a period of time
to observe the stability of the measured site response, in order to provide a reliable prediction of theperiod of potential earthquake motion at that site.
Nakamura’s technique describes the microtremors as Rayleigh waves propagating in a single layerover a half-space, and assumes that the microtremor motion is due to local sources such as traffic andhuman and construction activity nearby. It further assumes that the vertical component of groundmotion is not amplified by the soil layer. Hence, the spectral ratio of the horizontal to the verticalcomponents at the surface (H/V ratio) gives an estimate of the period at which it peaks, corresponding
to the site period.
The equipment used for the microtremor testing system consists of five velocity transducers; twohorizontal and one vertical, an amplifier and a laptop computer used for data acquisition. For theselection of the test location, care is taken to avoid heavy traffic, manholes, foundation sand other
underground structures. The sensors are placed so that the two horizontal sensors are orthogonal,
preferably facing North and East. The analysis is carried out using Nakamura’s method, plotting the
H/V spectral ratios that are the result of taking the RMS of the east and North spectral ratios. The
most significant peak of the H/V spectral ratio is taken to be the dominant frequency of the site.
Methods to get geophysical information from the microtremor measurement were 1) obtaining thephase velocity by array observation of microtremor and 2) obtaining H/V spectrum by using 3
component sensors. After obtaining the phase velocity or H/V spectrum, S-wave velocity profiles
should be interpreted by applying an inverse analysis. All 5 sensors were placed in a single row withthe distance of 15m and 30 min data was taken.
Soil characteristics can be assessed by Microtremor measurement. Hard soil gives high frequency andsoft soil gives low frequency. A structure may experience a vibration period at which it oscillates inthe earthquake vibration motion and will tend to respond that. Natural frequency is obtained based on
the spectral ratio of horizontal component of the structure to that of ground. Wave propagation
mechanism of Microtremor and its relation with ground vibration characteristics were studied fromthe beginning of Microtremor studies [11]. Figure 10 shows the microtremor testing equipment.

100Equipment arrangement

Microtremor Sensor

Figure 10: Microtremor Equipment

2.5 Data Collection Using Direct Shear Test
The direct shear test to measure the shear stress due of mortar bond of Old Academic Building of
BUET has been performed by using Hi-Force Hydraulic Jack. Figure 11 shows the testing activity of
direct shear test.

Figure 11: Direct Shear Test

3. Data Processing and Analysis
The analysis has performed using the GeoSiG software and D-Plot software. For microtremor
observation at the selected buildings, initially the sensors were deployed. Three sensors were fixed on
the different stories of the building and another one on the free field near the surface. After taking theobservation with the help of microtremor, the time domain velocity data was converted into to
frequency domain data and natural frequency if the structures are determined.

3.1 Curzon Hall Musa Khan Mosque
The intention of the tests described in this research was to provide some preliminary information
about the dynamic behavior. The Microtremor analysis of Curzon Hall Musa Khan Mosque has been
illustrated as below in figure 12 and figure 13.

101

1

1
0.7

0.7

Musa Khan Mosque-CH1

Musa Khan Mosque-CH2

0.5

0.5

0.3

0.3

0.2

0.2

0.1
0.07

CH2

CH1MOS

0.1
0.07
0.05

0.05
0.03

0.03

0.02

0.02
0.01

0.01

0.007

0.007

0.005

0.005

0.003

0.003
0.002
0.1

0.002
0.1

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

20

Frequency, Hertz

20

Frequency, Hertz

Figure 12: The corresponding FFT of recorded time series of the Curzon Hall Musa Khan Mosque
5
4

MUSA KHAN MOSQUE-SOIL

3

HVR

2

1
0.8
0.7
0.6
0.5
0.4
0.3

0.2
0.1

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

20

Freq (Hz)Figure 13: The corresponding H/V ratio of the Curzon Hall Musa Khan Mosque
3.2 Aambour Shah Shahi Mosque
Observation of microtremors can give useful information on dynamic properties of the site such as
predominant period and amplitude. Microtremor observations are easy to perform, inexpensive andcan be applied to places with low seismicity as well. The Microtremor analysis of Aambour Shah
Shahi Mosque has been depicted as below in Figure 14 and Figure 15.

3.3 Old Academic Building (OAB) of BUET
Seismic noise is relevant to any discipline that depends on seismology, such as geology, earthquake
engineering and structural engineering. It is often called ambient wave field or ambient vibrations.
The Microtremor analysis of Old Academic Building of BUET has been shown as below in figure 16
and Figure 17.

102

1

2
Ambar Shah Mosque-CH1

0.5
0.4
0.3

0.3

0.2

0.2
0.1
0.07
0.05

ch2

CH1 MOS

Ambar Shah Mosque-CH2

0.7

1
0.7
0.5

0.1
0.07

0.03

0.05
0.04

0.02

0.03
0.02

0.01
0.007
0.005

0.01

0.003

0.007

0.002
0.1

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

0.005
0.1

20

Frequency, Hertz

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

20

Frequency, Hertz

Figure 14: The corresponding FFT of recorded time series of the Aambour Shah Shahi Mosque
10
7

Ambar Shah Mosque-Soil

5
4
3

HVR

2

1
0.7
0.5
0.4
0.3
0.2

0.1
0.1

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

20

Freq (Hz)Karwan Bazar mosque Ambar Shah.xlsx

Figure 15: The corresponding H/V ratio of the Aambour Shah Shahi Mosque
0.00050.0005

CH02

2E-5
1E-5
5E-6
2E-6
1E-6
5E-7
0.1

OAB-CH2

0.00011E-5
1E-6

0.2 0.3 0.5

1

2 3 4 5 67 10

5E-8
0.1

20

0.2 0.3 0.5

1

2 3 4 5 67 10

20Frequency, Hertz

Frequency, Hertz

Figure 16: The corresponding FFT of recorded time series of the OAB
50
30

SOIL

20

Smoothed HV

C H 010.0002 OAB-CH1
0.0001
5E-5

10
7
5
3
2
1
0.7
0.5
0.3
0.2
0.1
0.07
0.05
0.1

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

6 7 8 910

20

Freq (Hz)Figure 17: H/V ratio of recorded time series of the OAB

103

3.4 Direct Shear Test of Old Academic Building (OAB) of BUET
Shear failure is the dominant mode of failure observed in many masonry buildings subjected to lateralloading due to earthquakes, wind (in tall and slender structures), support settlements, or
unsymmetrical vertical loading. Lateral loading can produce both diagonal cracking failures and shear
failures of the horizontal joints. Joint resistance is of particular concern in the analysis of the loadbearing unreinforced masonry structures that are rather common among older buildings in many
countries in the world. The shear generally acts in combination with compression caused by the selfweight and floor loads. Confinement by, for instance, structural frames to in-fill walls may also leadto shear compression.
The in-place shear test, also known as the push test, pro-vides a direct measurement of the shear
resistance of mortar joints in masonry. The test is suitable for masonry that has relatively strong units
and weak mortar so that shear cracks form in the typical stair step pattern along mortar joints and theunits remain uncracked. In this type of construction, the shear strength of the mortar joints limits theshear strength of the masonry wall [16].
The Uniform Code for Building Conservation (UCBC) provides an empirical relationship that relates
the mortar joint shear strength to the masonry wall shear strength, assuming that wall shear strength islimited by the shear of the mortar joints rather than shear through the units. The method is notapplicable for determining shear strength of modern masonry with high strength mortars [17].
A calculation on direct shear test of lime mortar as bonding material of Old Academic building has
been made. The calculation is given belowDirect Shear Test of Old Academic Building of BUETJack diameter
35 mm
Area
962.12 mm2Brick Size
Contact Area
Dial Gauge Reading
Shear Strength of the Sample, τNos. of bricks above testing brick
Height of wall above testing brick
Unit weight of wall
Vertical Pre-stress on testing brick, σσ* μShear Stress due to mortar bond only

254 mm (Length); 114.3 mm (Width)
77419.2 mm2650(Kg/cm2); 89846.22 (N)1.161 N/mm2
100 Nos.
9.15 m
19 KN/m3
173.85 KN/mm2
0.174 N/mm2
τ-σ* μ = 0.987 N/mm2

Reliable information on shear resistance is needed when performing retrofits and seismic upgrades ofmasonry buildings. While shear strength of a masonry wall is difficult to measure without resorting tolarge-scale testing, less destructive in-place tests of single masonry units provide a comparative figure104that can be correlated to full-scale wall behavior. This less destructive alternative is more economical
than large-scale testing and is desirable when a building’s historic integrity must be maintained.

4. Results and Discussions
For the three buildings described earlier in this paper, both vertical and horizontal measurements wererecorded, with a sampling rate of 200Hz and duration of 30 minutes for each. From the analysis of thenormalized H/V ratio plots and FFT of the three buildings, the pertinent information obtained ispresented in Table 1.
Table 1: Comparison of Microtremor Result of Soil (H/V ratio) and Building (FFT)
Test points

Predominantof Soil (HVR)

Curzon Hall Musa 1.8 Hz

Frequency Structural Predominant Remarks
Frequency
3.6 HzKhan Mosque
Aambour Shah Shahi 1.2 Hzofnoseismic resonance
2.6 HzMosqueOld

Possibility

Possibilityofnoseismic resonanceAcademic 1.6 Hz

Building of BUET

1.9 HzPossibility of seismic
resonance

The predominant frequency of the building of the Curzon Hall Musa Khan Mosque has found 3.6 Hz
which is different from the predominant frequency of the site soil (1.8 Hz). So there’s no possibility ofsoil strucrutre interaction during any severe earthquake. It is also similar in case of the Aambour Shah
Shahi Mosque. But the predominant frequency of building of the Old Academic Building of BUET isin the range of the peak frequency of the soil. This value is close to the range of the higher modes ofvibration for the buildings measured as shown in the figure 16 and figure 17. This raises thepossibility of soil-structure interaction.
The direct shear test was done to find the mortar strength. From the analysis the shear stress due tomortar bond only was found about 0.987 N/mm2 which is below the standard value. The direct shear
test result suggested that as the mortar bond was not strong enough, the OAB building will be unable
to resist lateral forces due to an strong earthquake. A detailed assessment has been done by following
the guidelines of Arya (1986)[18]. Retrofitting of the masonry wall is mandatory. Currently, the OAB
is being retrofitted.

105

5. Conclusions
The intention of the tests described in this paper was to provide some preliminary information about
the dynamic behavior and the dynamic site conditions for three masonry buildings in Dhaka City. The
Curzon Hall Musa Khan Mosque, Aambour Shah Shahi Mosque and the Old Academic Building(OAB) of BUET were each tested by researchers of BUET. Among the three historical buildings,
from the dynamic analysis it has found that two buildings (Curzon Hall Musa Khan Mosque,Aambour Shah Shahi Mosque) are safe from seismic resonance whereas the Old Academic Buildingof BUET has the strong probability of severe seismic resonance. Also the direct shear test result onbrick mortar of OAB shows that the mortar strength is below the standard value which indicates thatthe load bearing masonry wall is unable to withstand the lateral seismic force. This means the OAB
needs to be retrofitted. In this case, the earthquake resistant guidelines for non-engineered
construction of Arya (1986) have been followed to retrofit the OAB.

References[1] https://en.wikipedia.org/wiki/Architecture_of_Bangladesh[2] http://en.banglapedia.org/index.php?title=Architecture[3] http://en.banglapedia.org/index.php?title=Mosque_Architecture[4] https://en.wikipedia.org/wiki/Kantajew_Temple[5] PAGE, A.W., KLEEMAN, PW., STEWART, M.G., and MELCHERS, RE., “Structural aspects of
the Newcastle Earthquake” Proceedings of the Institute of Engineering, Australia Structural
enginnering Conference, Adelaide, South Australia; 3-5 October, 1990.
[6] De Stefano A., Clemente P. (2009). “Structural health monitoring of historic buildings”, In
Karbhari V.M. and Ansari F. (Eds), Structural Health Monitoring of Civil Infrastructure Systems,
Woodhead Publishing Ltd[7] Clemente P., Rinaldis D. (2005). “Design of temporary and permanent arrays to assess dynamic
parameters in historical and monumental buildings”. In Ansari F. (ed), Sensing Issues in Civil
Structural Health Monitoring (Proc., North American Euro-Pacifi c Workshop, CSHM, Honolulu, 1013 November 2004, invited paper), Springer, 107-116.
[8] Rinaldis D., De Stefano A., Clemente P. (2005). “Design of seismic arrays for structural
systems”.In Ou J.P., Li H. & Duan Z.D. (eds), Structural Health Monitoring of Intelligent
Infrastructure (Proc., 2nd International Conference SHMII-2, Shenzhen, Nov.16-18, 2005), Vol. 2,
1447-1453, Taylor & Francis/Balkema, Leiden, The Netherlands.
[9] De Stefano A., Clemente P. (2005). “S.H.M. on historical heritage. Robust methods to face large
uncertainties”.Proc., 1st International Conference on Structural Condition Assessment, Monitoring106

and Improvement, (12-14 Dec. 2005, Perth, W. Australia), 09-22, CI-Premier Conference
Organisation, Singapore.
[10] Clemente P., Buffarini G. (2009). “Dynamic Response of Buildings of the Cultural Heritage”, In
Boller C., Chang F.K., Fujino Y. (eds), Enciclopedia of Structural Health Monitoring, John Wiley &Sons Ltd, Chichester, UK, 2243-2252.
[11] Aki, K. (1957). Space and time spectra of stationary stochastic waves, with special reference tomicrotremor. Bull. of earthquake research Institute , 415-456.
[12] Nakamura, Y. (1989) “A method for Dynamic Characteristics Estimation of Subsurface using
Microtremor on the Ground Surface”, QR of RTRI, Vol. 30, No. 1, pp. 25-31[13] Seismic Evaluation of Existing Buildings, ASCE/SEI 31-03.
[14] Van Zijl, G. P. A. G. (2004). “Modeling masonry shear-compression: Role of dilatancy
highlighted.” J. Eng. Mech., 10.1061/ (ASCE) 0733-9399 (2004)130:11(1289), 1289–1296.
[15] Lourenço, P. B., Rots, J. G., and Blaauwendraad, J. (1998). “Continuum model for masonry:
Parameter estimation and validation.”J. Eng. Mech., 10.1061/ (ASCE) 0733-9445(1998)124:6(642),
642–652.
[16] ASTM C 1531-02, Standard Test Methods for In Situ Measurement of Masonry Mortar Joint
Shear Strength Index.
[17] Uniform Building Code (UBC) Standard 21-6, In Place Masonry Shear Tests.
[18] A. S. Arya (1986). Guidelines for Earthquake Resistant Non-engineered Construction.
International Association for Earthquake Engineering. p. 158

107

PART-X

EFFECTS OF RELATIVE DENSITY AND
EFFECTIVE CONFINING PRESSURE ON
LIQUEFACTION RESISTANCE OF SANDSBANGLADESH NETWORK OFFICE FORURBAN SAFETY (BNUS), BUET, DHAKA

Prepared By: Mohammad Mominul Hoque
Mehedi Ahmed Ansary1081 INTRODUCTION
The first widespread observations of damage attributed to soil liquefaction were made in the1964 Niigata and Alaska earthquakes. Spectacular examples of liquefaction induced failure
have also been widely observed during most moderate to large size earthquakes around theworld. Since 1964 Alaska and Niigata earthquakes, liquefaction has been studied extensively
by many investigators and substantial advances have been made in both understanding andpractice with regard to assessment and mitigation of liquefaction induced hazards. However,major advances have occurred in the field of seismically induced soil liquefaction,catastrophic failures in recent earthquakes have provided a sobering reminder thatliquefaction of soils as a result of earthquake poses a major threat to the safety of
infrastructures. There is no reported case history of seismically induced soil liquefaction in
Bangladesh, but location of this country in world seismic map, geologic formation andfrequent earthquakes in and around the country remind the great danger of seismicallyinduces soil liquefaction. This research aimed to examine the effects of relative density andinitial effective confining pressure on liquefaction resistance of saturated sands using
laboratory cyclic triaxial test.
2 LITERATURE REVIEWThe effects of relative density and initial effective confining pressure on liquefaction
resistance of saturated sands undercyclic loading condition have been extensively
investigated by many researchers in the laboratory cyclic triaxial tests. The outcome of thesestudies generally agreed that, the resistance to liquefaction of sands tends to increase with anincrease in relative density and decrease with increase in effective confining pressure.
Extensive laboratory investigations on Toyoura sand revealed that, up to a relative density of
70%, liquefaction resistance tends to increase linearly with the relative density, but for thedensity in excess of 70%, the cyclic strength goes up sharply (Tatsuoka et al. 1986).
Undrained cyclic triaxial tests results on clean Ottawa sand (Carraro et al. 2003) and whitenatural quartz sand (Stamatopoulos 2010) have also illustrated that,the resistance toliquefaction increases as the relative density increases. Other laboratory studies (Liu and Xu
2013, Belkhatir et al. 2010, Vaid and Sivathayalan 2000) have equally provided strong
evidence that the liquefaction resistance of sand increases with increase in relative density.
Laboratory research on rounded Ottawa sand and angular tailing sand illustrated that,
substantial decrease in resistance to liquefaction occurred for both sands with increase in109

effective confining pressure in the range of 200 kPa to 2500 kPa (Vaid et al. 1985). It wasapparent that, the resistance to liquefaction for both sands at all level of confining pressure
tends to converge around a relative density of 50-55%. This implies that, the influence ofconfining pressure on reduction of resistance against liquefaction may be significant only fordensities larger than a certain minimum. In addition, laboratory test results confirmed that,
initial effective confining stress does not have any influence on the resistance to liquefaction
at loose density (Dr = 19%) state (Thomas 1992). But at high relative densities of 40% and59%, resistance to liquefaction decrease with increase in initial effective confining stress,
height decrease being associated with the densest state. So, it is obvious that resistance toliquefaction of sand decrease with increase in initial effective confining pressure and thiseffect is more pronounced as the sand specimens become denser.
A significant amount of research has been conducted in the field of soil liquefaction aroundthe world, but there are very limited numbers of laboratory research (Hoque et al. 2013,
Karim and Alam, 2014) have been undertaken to evaluate liquefaction resistance of local
soils. A study was therefore carried out to examine the liquefaction resistance of locallyavailable soils.
3 EXPERIMENTAL INVESTIGATIONS
3.1 Test Materials
For this research, two different types of poorly graded sands were collected; one fromsubsurface at Rooppur, Pabna and another from the bed of Piyain river at Jaflong, Sylhet.
Index properties of the tested sands are given in Table 1. Both sands are grey in color andcomposed of subrounded particles in shape. According to Unified Soil Classification Systemthese sands are classified as poorly graded sands with silt (SP-SM).
Table 1.Index properties of the sands
Index Properties
Specific gravity
Fineness Modulus
Mean grain size,
D50 (mm)Fines (%)
Minimum density(kN/m3)
Maximum density(kN/m3)

Rooppursand
2.66

Piyain river
sand
2.65

0.5

1

0.15

0.21

13

11.7

13.15

12.15

17.95

16.7

110

Particle size distribution curves for Rooppur sand and Piyain river sand are presented in
Figure1. From these curves it can be observed that, both sand samples contain appreciable
amount of fine particles.
3 .2 Specimen Preparation
Soil specimens of size 142 mm in height and 71 mm in diameter were prepared using wet
tamping technique. After taking required amount of dry sand in a container, a measured
amount of de-aired water was added to the sand to bring the moisture content approximately
to 10 percent by weight of dry sand. The sand and water was then mixed thoroughly and thecontainer was sealed and kept for half an hour to insure uniform water content distribution
throughout the sand. The moist sand was then placed into the mold in six separate layers ofequal mass and thickness. The layer mass was determined from the target relative density ofthe specimen. Each layer was compacted using a manually operated aluminum hammer ofdiameter 35.5 mm, weight of 1000 gm and equipped to provide a free fall height of 152.4
mm. The numbers of blows required on each layer to achieve target relative density wasdetermined by several trials.
A total of 26 soil specimens were prepared using Rooppur sand at three different relative
densities of 30%, 50% and 70% and tested at a constant initial effective stress of 100 kPa.
Using Piyain river sand, a total of 11 specimens were prepared at a constant relative densityof 55% and tested at two different effective confining pressures of 50 kPa and 100 kPa. In
both test series, cyclic stress ratio was kept in the range of 0.10 to 0.40.

Rooppur sandPiyain river sandFigure 1.Particle size distribution curves
3.3 Cyclic Triaxial Test
The prepared specimen was sealed in a water tight rubber membrane with O-ring andconfined in a triaxial chamber where it was subjected to a confining pressure of 20 kPa. In

111

order to improve initial saturation of the specimen, carbon dioxide (CO2) was allowed to flow
through the specimen at a low pressure (less than 20 kPa) in order to replace the air in thespecimen pores. This was done because CO2 has a much higher solubility in water than air,allowing a higher degree of saturation to be reached at lower backpressure. After 30 minutes,
the flow of CO2 was stopped and a tank of de-aired water was attached to the drainage line on
the bottom platen. The de-aired water was then percolated from the bottom trough the top of
the specimen by gravitational force in order to increase the degree of saturation andpercolation was continued until all CO2 from specimen’s pores has been replaced. Once thedesired volume of de-aired water had flowed through the specimen, the drainage valves on
the cell were closed and the de-aired water line removed. The drainage line is then connectedto the pore pressure line.The specimen was then saturated with de-aired water using
backpressure saturation. The backpressure was increased gradually while maintaining theeffective confining pressure at 10 kPa. This process was continued until the Pore Pressure
Parameter B value exceeded 0.95. Following saturation, the sand specimen was isotropicallyconsolidated to desired effective stress.At the end of the consolidation it was ensured that thepore pressure parameter B remains unchanged.
Undrained cyclic loading was then applied on the specimen using stress controlled method.
The magnitude of cyclic load to be applied on the soil specimens for the desired cyclic stressratio was automatically calculated by operating software based on the initial input
parameters. In the entire test program, a harmonic cyclic load was applied using sine wave
with a frequency of 1 Hz. The maximum peak to peak axial strain of 10% was recorded. The
numbers of loading cycles was limited to 200 cycles with a specified data recording speed of
100 data points per cycle to give the adequate resolution to measure sample response in termsof load, deformation and pore water pressure. During the whole test procedure enormous
amount of data were recorded such as axial deformation, cell pressure, cyclic load, andsample pore water pressure, normal stress, and shear stress using the cyclic triaxial software.
3.4 Data calculation
As the deviator stress cycles between compression and extension, pore water pressures in thespecimen builds up steadily, effective stress decreases, and the specimen undergoes axial
deformation. Excess pore water pressure builds up steadily with the applied loading cycles,
and eventually approaches a value equal to the initially applied confining pressure, thereby
producing an axial deformation of about 5% in double amplitude. Such a state has beenreferred to as initial liquefaction or simply liquefaction. Typical undrained response of a112

specimen in the form of deviator stress, axial deformation and induced excess pore waterpressure with number of loading cycles obtained at cyclic stress ratio of 0.22 and initialeffective confining stress of 100 kPa at relative density of 50% are given in Figure 2.

Figure 2. Typical undrained response of a specimen (a) deviator stress, (b) axial strain, and(c) induced excess pore water pressure with number of loading cycles
It can be seen from Figure 2 that, under constant amplitude of cyclic deviator stressapplications the excess pore water pressure increases gradually and reached the value justequal to the initial applied effective confining pressure. At the beginning of the testdevelopment excess pore water pressure in the specimen is relatively slow and the axial
deformation in the specimens is small. As the pore water pressure start to increase rapidly,
axial deformation also speeds up. When excess water pressure reached just equal to initialeffective confining pressure, it take only few cycles to reach 5% double amplitude axial
strain, which is defined as initial liquefaction.

113

For each cyclic stress ratio, number of cycles required to reach 5% double amplitude axial
strain are recorded. Such data from several tests are then combined and plotted as cyclic
stress ratio versus number of cycles required to reach initial liquefaction, which is commonly
known as liquefaction resistance or cyclic triaxial test strength curve. From cyclic strength
curve, the liquefaction resistance of the specimen is specified in terms of magnitude of cyclic
stress ratio (CSR) required to reach 5% double amplitude axial strain in 20 cycles of uniform
load application.
4 RESULTS AND DISCUSSION
4.1 Effects of relative density
Cyclic shear strength curves constructed based on 26 undrained cyclic triaxial tests on
Rooppur sand at three different relative densities are shown in Figure 3 and the assessedliquefaction resistance corresponding to relative densities of 30%, 50% and 70% are 0.15,
0.21 and 0.24 respectively. It can clearly be seen from Figure 3 that, the increase in relative
density results in increase in liquefaction resistance. Controlling initial test conditions andtest procedures identical it was noticed that, the change in relative density from 30% to 50%
results in 40% increase in liquefaction resistance, while change in relative density from 30%
to 70% results in 60 % increase in liquefaction resistance. It is also apparent that the cyclic
strength curve corresponding to each relative density shifts consistently to the right along xaxis as the relative density becomes higher. Which implies that, the number of cycles
required to occur initial liquefaction increase with increase in relative density. So, an increase
in relative density causes significant increase in resistance against liquefaction, thereby
making soils less susceptible to liquefaction.
SP-SM= 100 kPa
B = 0.95
f = 1 HzDA = 5 %Figure 3. Cyclic shear strength curves for relative density of 30%, 50% and 70% at initialeffective confining pressure of 100 kPa

114

4.2 Effect of Confining Pressure
Liquefaction resistance curves generated based on a total of 11undrained cyclic triaxial tests
on Piyain river sand at two different initial effective confining pressure of 50 kPa and 100
kPa at a constant relative density of 55% are depict in Figure 4. It can be clearly seen from
Figure 4 that, increase in initial effective confining pressure results dramatic reduction ofresistance against liquefaction. Remaining initial test conditions and test procedures identicalit was observed that, an increase in initial effective confining pressure from 50 kPa to 100
kPa caused liquefaction resistance to decrease from 0.30 to 0.12. Hence, soils at higheffective confining stress are more susceptible to liquefaction than those at low effective
confining pressure.
SP-SM
Dr = 55%
B = 0.95
f = 1 HzDA = 5%==Figure 4. Cyclic shear strength curves for initial effective confining pressure of 50 kPa and100 kPa at relative density of 55%
5 CONCLUSIONS
Series of laboratory undrained cyclic triaxial tests were carried out on two different sands at
different relative densities and effective confining pressures in order to examine the effects ofrelative density and initial effective confining pressure on liquefaction resistance of saturated
sands. Two local sands were used in this investigation. Laboratory tests results illustrated
that, relative density and initial effective confining pressure has great influence onliquefaction resistance. Increase in relative density results significant increase in resistanceagainst liquefaction. The rate of increase is almost linear with relative density. On the other
hand, resistance against liquefaction decreased dramatically as the initial effective confiningpressure increased. As the initial effective confining pressure was doubled from 50 kPa to
100 kPa, the value of CSR decreased to about one-third from the value at initial confiningpressure of 50 kPa. The results obtained in this research are reasonably in agreement with theresults reported in literature considering initial test conditions and test procedures.
115

4 REFERENCES
Tatsuoka F., OchiK.,Fujii S. and Okamoto M. 1986b. Cyclic undrained triaxial and torsional
shear strength of sands for different sample preparation methods. Soils andFoundations26(3), 23- 41.
Carraro J.A.H., Bandini P. and Salgado R. 2003. Liquefaction resistance of clean andnonplastic silty sands based on cone penetration resistance. Journal of geotechnical andgeoenvironmental engineering 129 (11), 965-976.
Stamatopoulos C.A. 2010. An experimental study of the liquefaction strength of silty sands interms of the state parameter. Soil Dynamics and Earthquake Engineering30 (8), 662-678.
Liu C. and Xu J. 2013. Experimental study on the effects of initial conditions on liquefactionof saturated and unsaturated sand. International Journal of Geomechanics 15 (6),04014100.
Belkhatir M., Arab A., Della N., Missoum H., and Schanz T. 2010. Liquefaction resistance ofchlef river silty sand: effect of low plastic fines and other parameters. Acta Polytechnica
Hungarica 7 (2), 119-137.
Vaid Y.P. and Sivathayalan S. 2000. Fundamental factors affecting liquefaction susceptibilityof sands. Canadian Geotechnical Journal 37 (3), 592-606.
Vaid Y., Chern J. and Tumi H. 1985. Confining pressure, grain angularity and liquefaction.
Journal of geotechnical and geoenvironmental engineering 111 (10), 1229–1235.

116

PART-XIEVALUATION OF LIQUEFACTIONPOTENTIAL FROM SPT AND CPT: A
COMPARATIVE ANALYSISBANGLADESH NETWORK OFFICE FORURBAN SAFETY (BNUS), BUET, DHAKA

Prepared By: Mohammad Mominul Hoque
Mehedi Ahmed Ansary117

1 INTRODUCTION
The Standard Penetration Test (SPT) and Cone Penetration Test (CPT) are the two mostwidely used in-situ tests for evaluating the liquefaction characteristics of soils.Thebasic
framework for liquefaction evaluation methods (Seed and Idriss, 1971) based on SPTfirstbegan to evolve afterthe wake of a pair of devastating earthquakes that occurred in Alaska
and Niigata in 1964.Countless effort of numerous researchers(Seed et al. 1985, 2003, Youd etal. 2001, Boulanger and Idriss, 2014) have made subsequent progresses of liquefaction
evaluating methods and continue to evolve today. The SPT based deterministic relationship(Seed et al. 1985) is one of the most widely accepted correlation for evaluation of seismicallyinduced soil liquefaction and which has set standard for practicing engineers. On the other
hand, CPT based correlations is increasingly used for liquefaction studies because of its
consistency and efficiency, and is now represent nearly co-equal status with regard toaccuracy and reliability relative to SPTbased correlations. The fundamental of both methods,
as adopted by numerous researchers, compares the earthquakeinducedcyclic stress ratios(CSR) with the cyclic resistance ratios (CRR) of the soil, usually determined from in-situ
parameter such as SPT N-value or CPT cone tip resistance.Both SPT and CPT methods havesignificant relative advantages, and both tests are far batter when used in combinations. This
research intended to evaluate and compare liquefaction potential using both SPT and CPT
based deterministic correlations.
2 FIELD INVESTIGATIONSIn this research, field investigations were carried out along the riverbank of the Jamuna River,Bangladesh. The geologic formations of the research site are mainly consisting of alluvial
sand and silt deposits of Holocene age. The alluvial sands are light to brown-grey coloured,coarse to fine silty sand of subrounded in shape. The sand contains mostly quartz, feldspar,mica and significant amount of heavy minerals. The alluvial silts have the same color as the
sands, but are fine sandy to clayey silt and are poorly stratified (Alam et al. 1990).
A total of four pairs of SPT and CPTtests were performed in different locations within the
study area and each pair was carried out as close as possible, maximum horizontal distance
not greater than 10m. Boreholes for the SPT were advanced by percussion method withbentonite slurry and an automatic type SPT hammer-release was used for the measurement ofN-values from SPT. Potential source of uncertainty that may affect N-values have been
carefully taken into account. The split spoon sampling method was used to obtain118

representative disturbed soil samples from boreholes and used for laboratory investigations.
The SPT N-value and samples were collected every 1.52 m intervals.
CPT soundings were advanced using a Hogentoglar type piezocone penetrometer with across sectional area of 10 cm2 and which can measures the pore water pressure (u2), as well as
the cone tip resistance (qc) and sleeve friction (fs). To perform CPT sounding, the cone waspushed vertically into the ground at a constant rate of approximately 20 mm/sec. During theadvancement, measurements of dynamic pore water pressure, cone tip resistance and sleeve
friction were recorded continuously at increments of 10 mm. The modified cone tip resistance(qc,1,mod) in MPa (top scale) andnormalized SPT N1,60 values (bottom scale) are presented in
Figure 1.
05Borehole - 1
10
15

0

20

0

5

Borehole - 2
10
15

0

20

5

Borehole - 3
10
15

20

20

60

0

.CPT– qc,1,mod.SPT– N1,60

5

Depth (m)Depth (m)

5

10

10

15

15

20

20
0

20

40

60

0

20

40

60

0

40

Figure 1. Penetration depth vs.modified cone tip resistance qc,1,mod and normalizedN1,60 values
for all boreholes.
It has been found that, the soils within the test area primarily comprised of silt, fine andmedium sands, and clay. As such, the combination of silt and sand are generally non-plastic
and the combination of silt, clay and sand are low-plastic. Soils are moist from groundsurface and ground water table is located approximately at 3 m below from ground surface.
Density state of soil at different depths varies from loose to medium dense.

3 LABORATORY INVESTIGATIONSLaboratory investigations included mainly visual observations and mechanical sieve analysis.
Soil samples recovered from various depths were individually assessed and classified basedon sieve analysis. Samples are light brown to grey in colour and grains are mostly
subrounded in shape. Out of 52 recovered samples, 44 samples were used for sieve analysis.
Soil samples obtained from 1.52 m and those contained considerable amount clay were
excluded from sieve analysis. From sieve analysis it was observed that soils are containing
appreciable amount of fines (material finer than 0.075 mm) ranging from 3.5 to 39.2 percent,fineness modulus (F.M.)varied from 0.18 to 1.11 and mean grain size (D50) in the range of
0.09 to 0.23 mm. Based on the sieve analysis results, the soils were generally classified into
two groups; either well graded sands with little silt or poorly graded sands with silt.
According to unified soil classification system, the soils can be symbolized as SW and SPSM respectively. As fines content is one of the important parameter in liquefaction analysis
fromdeterministic relationships, only fines content for each borehole are presented in Table 1.
Table 1. Fines content of sand at different boreholes.
Depth
BH-3
BH-4
BH-1
BH-2
(m)
3.05
26.8
ND*
17.96
ND*
4.57
32.5
32.44
16.89
ND*
6.10
32.5
26.39
19.8
ND*
7.62
38.4
36.35
20.7
5.85
9.14
11.3
39.2
16.95
6.25
10.67
12.4
38.1
17.8
5.5
12.19
8
38
7.44
5.5
13.72
17.3
22
5.5
5.39
15.24
12.5
24.4
4.15
5.4
16.76
7.68
5.85
5.05
5.15
18.29
32.03
7.5
4.95
6.75
19.81
22.7
6.85
3.5
6
BH = Borehole and ND* = not determined

4 DATA ANALYSISThe SPT and CPT based deterministic relationships compares the earthquake-induced cyclic
stress ratios (CSReq) with the in-situ equivalent uniform cyclic stress ratios (CSReq,M=7.5,1atm)of the soil. The soil’s CSReq,M=7.5,1atm is correlated to in-situ parameters obtained from SPT
blow count (N-values) and CPT penetration resistance (cone tip resistance, qc). The measured

120

SPT N-values, normalized for both effective overburden stress and energy, equipment andprocedural factors affecting SPT testing to N1,60 values and CPT cone tip resistance, qc isnormalized and modified to qc,1,mod for effective overburden stress and the frictional effects ofapparent fines content and character. Normalized N1,60 and modified qc,1,mod is then used to
calculate CSReq,M=7.5,1atm from deterministic relationships.In the deterministic correlations
both N1,60and qc,1,modrepresented as a function of fines content. It should be noted that,
CSReq,M=7.5,1atm is obtained after adjusting both for magnitude-correlated duration weighting
factor and effective initial overburden stress (expressed through a Kσ factor). Factor of safety(often known as liquefaction potential or liquefaction resistance) against liquefaction can now
be obtained from the ratio of CSReq,M=7.5,1atm to CSReq. In general, it is assumed that, if thevalue of safety factor greater than unity, the deposit is safe against liquefaction for a given
earthquake.
4.1 Earthquake-induced Cyclic Stress Ratio
The earthquake-induced cyclic stress ratio, at a given depth, within the critical soil stratum, isusually expressed as a representative value (or equivalent uniform value) equal to 65% of the
maximum cyclic shear stress ratio as –
CSR

0.65

a

σ /σ′

/g

r

(1)

Where, σ and σ′ are the vertical total stress and effective stress at a given depth, a/g is

the maximum horizontal acceleration (as a function of gravity) at the ground surface, and r
is the shear stress reduction factor that accounts for the dynamic response of the soil profile.
In this research maximum horizontal acceleration at the ground surface was taken 0.25g andvalues ofr were estimated from the depth vs. r correlation (after Cetin and Seed, 2000).
4.2 In-situ Uniform Cyclic Stress Ratio
The measured SPT N-values were first corrected for effective overburden stress, energy,
equipment, and procedural effect to obtained fully standardized N1,60 values as –
N,

1/σ′

.

C

C

C

C

(2)

Where,C is the correction for rod length, C is the correction for non-standardized sampler
configuration, C is the correction for borehole diameter, andC is the correction for hammer
energy efficiency.

121

Similarly, measured cone tip resistances, qc were normalized and modified for effective
overburden stress and the frictional effects of apparent fines content and character to obtained
to qc,1,mod values as
q, ,

q

P /σ′

Aq

(3)

Where, P is the atmospheric pressure, normalization exponent (c) is a function of bothnormalized tip resistance (qc,1) and friction ratio (Rf), Aq is the function of qc,1, Rf and c.
Then, normalized N1,60 and modified qc,1,modwere used to calculate CSReq,M=7.5,1atmfrom
deterministic relationships (Seed et al, 2003). An earthquake magnitude of Mw = 7.5 wasassumed for the adjustment of magnitude-correlated duration weighting factor. Soil’s unit
weights were back calculated from SPT N-value vs. unit weight correlation (Bowles, 1982) toestimate total and effective overburden stresses.

5 RESULTS AND DISCUSSIONS
Factor of safety obtained from SPT and CPT based deterministic relationships are presented
in Figure 2 for different boreholes. As SPT N-values were recorded every 1.52 m intervals,
factor of safety for both SPT and CPT were also evaluated at same depth intervals. In case of
CPT, an average value of cone tip resistances over 0.30 m were taken as penetration
resistance, at same depths where SPT blows were counted. For all boreholes it can beobserved from Figure 2 that, majority of the cases safety factors obtained from CPT based
relationship gives lower values as compared to SPT based relationship. Although safety
factors obtained both SPT and CPT are found to be mostly identical throughout the boreholes
depth, for some depths, factor of safety obtained from CPT are higher than that from SPT.
Safety factors obtained from CPT analysis indicate that, liquefaction can occur throughout
the entire depth of 20m in all the boreholes, except some thin layers in borehole-2 andborehole-3. On the other hand, safety factors obtained from SPT analysis indicate thatliquefaction can be expected in all borehole locations at depths less than 10 m and 12.5 m inborehole-1 and borehole-2 respectively.

122

Figure 2. Factor of safety against liquefaction from SPT and CPT.
Inconsistency in safety factors evaluated from SPT and CPT may be resulted due to thevariations in recorded SPT N-values and CPT cone tip resistances at same depth. Probably
these variations were due to boreholes distance between each pair of SPT and CPT. In
addition to that, energy efficiency of SPT hammer was not directly estimated in the field andefficiency ratio was assumed as 60% of the applied energy. Due to this reason, factor ofsafety against liquefaction from SPT may have resulted in over estimation compared to CPT.

6 CONCLUSION
Four pairs of SPT and CPT tests were carried out to evaluate and compare liquefaction
potential from SPTand CPT based deterministic relationships. It was observed that, therecorded SPT N-valueand CPT resistance considerably vary at same depth. Due to thisinconsistency, safety factors against liquefactionresults an over and/or under estimationcompare to each other. So, it is highly recommended to ensure high quality tests data to
confirm accurate and reliable results when both methods are used in combinations.

123

7 REFERENCES
Alam M.K., Hasan S.A.K.M., Khan M.R. and Whitney J.W. 1990.Geological Map ofBangladesh.Geological Survey of Bangladesh, Dhaka.
Bolton Seed H., Tokimatsu K., Harder L.F. and Chung R.M. 1985. Influence of SPT
procedures in soil liquefaction resistance evaluations. Journal of Geotechnical Engineering
111(12), 1425-1445.
BoulangerR.W.and IdrissI.M. 2014. CPT and SPT based liquefaction triggering procedures.
Rep. No. UCD/CGM-14, 1.
Bowles, J.E. 1982. Foundation Analysis and Design. McGraw-Hill, New York.
Cetin K.O. and Seed, R.B. 2000. Earthquake-Induced Nonlinear Shear Mass Participation
Factor (rd). Geotechnical Engineering Research Report No. UCB/GT2000/08. Universityof California, Berkeley.
Seed H.B. and Idriss I.M. 1971. Simplified Procedure for Evaluating Soil Liquefaction
Potential. Journal of the Soil Mechanics and Foundations Division 97 (9), 1249-1273.
Seed, H. B., Tokimatsu, K., Harder, L. F., Chung, R. M. 1985. Influence of SPT proceduresin soil liquefaction resistance evaluations. Journal of Geotechnical Engineering, 111(12),1425-1445.
Seed R.B., Cetin K.O., Moss R.E. Kammerer A.M., Wu J., Pestana J.M., Riemer M.F.,
Sancio R.B., Bray J.D., Kayen R.E. andFaris A. 2003. Recent advances in soil liquefactionengineering: a unified and consistent framework. In Proceedings of the 26th Annual ASCE
Los Angeles Geotechnical Spring Seminar.Long Beach, California.
Youd T.L., Idriss I.M., Andrus R.D., Arango I., Castro G., Christian J.T., Dobr, R., Finn
W.L., Harder Jr L.F., Hynes M.E. and Ishihara K. 2001. Liquefaction resistance of soils:
summary report from the 1996 NCEER and 1998 NCEER/NSF workshops on evaluationof liquefaction resistance of soils. Journal of geotechnical and geoenvironmental
engineering127(10), 817-833.

124

PART-XII

CPT-SPT BASED CORRELATIONS FORCOHESIONLESS SOIL FOR UTTARA 3RD
PHASE, DHAKABANGLADESH NETWORK OFFICE FORURBAN SAFETY (BNUS), BUET, DHAKA

Prepared By: Zinan A. Urmi
Mehedi Ahmed Ansary

125

1

INTRODUCTION

Standard Penetration Test (SPT) and Cone penetration Test (CPT) are the most commonlyused in situ tests to demarcate soil stratigraphy. It is also important for determining thegeotechnical engineering properties of surface/ subsurface soils. Several geotechnical design
parameters of the soil are associated with the SPT. On the contrary CPT is becoming
progressively more popular for site investigation and geotechnical design, based on the soil
type and testing method. For many construction projects, SPT for the preliminary soil
investigation is generally used, while CPT is used for detailed soil investigation andconstruction quality control. For this reason, it is very imperative to correlate the SPT Nvalue to CPT data so that the available data could be effectively utilized.

2

BACKGROUND

Since last few decades, much research has taken place to properly utilize abundant
experiences and available database on SPT to more reliable CPT. As a result, a considerable
number of correlations have been proposed by several researchers between CPT cone tip
resistance (qc), SPT N-values and other engineering soil properties. These correlations can beconsidered in three major groups. Most of the primary correlations considered qc/N60 as afunction of grain characteristics, such as mean grain size (D50) and/or fines content (fc). Someother researchers proposed a constant value of qc/N60 for different soil types in a chart ofcorrected cone tip resistance (qt) versus friction ratio (Rf).
Many researchers have pointed out the importance of CPT -SPT correlations, it shows that
there is a need for reliable CPT-SPT correlations so that CPT data can be used in existing
SPT-based design approaches.
Kulhawy and Mayne emphasize on the advantages of having a procedure to interrelate N60
and qc. These tests represent the most common in situ soil testing used worldwide and both ofthem representing soil resistance to penetration (although the SPT is dynamic and the CPT is
quasi-static).
Back in the late 1950s and early 1960s, several researchers suggested constant values of
qc/N60 for different soil types. A number of researchers proposed that the qc/N60 ratio is afunction of the mean grain size (D50) of the soil. They concluded that the smaller the qc/N60
ratio, the finer grained the soil. The proposed classification chart was recommended to126estimate the mean particle size. Clearly, the qc/N60 ratio increases with increasing grain size(D50); conversely, the ratio decreases with increasing fine material. Scatter in data tends toincrease with the increase in sand grains size (D50 1.0 mm). This may have related to thesignificant effect of large particles on the penetration.
Other investigators reported that the correlation could be more relevant by relating the finecontents (Fc) to the qc/N60 ratio. Similarly, their study results indicate that the qc/N60 ratio issmaller with sands of high fines content than for clean sands. Kulhawy and Mayne havecompiled a number of studies in one graph to verify a general trend between the qc/N60 ratio
and the fines content. The N60-values used in that research were the uncorrected due to some
limitation of the data.
Robertson et al. (1983) presented the qc/N60 ratio as a function of mean grain size, ‘D50’.
They proposed a soil behavior-type classification, giving qc/N60 ratio for each soil
classification zone based on cone penetration test with pore pressure measurement tests(CPTU, piezocone).
Ismael and Jeragh (1986) correlated CPT qc values with SPT N-values for calcareous desert
sands in Kuwait and compared their results with the values presented by Schmertmann(1970) for clean, fine to medium sands and slightly silty sands. Their proposed n- values werehigher than those proposed by Schmertmann for clean, fine to medium sands and slightly
silty sands. A close agreement of their test results in the form of qc/N60 versus mean grain
size ‘D50’ where found when compared with the historical data of Robertson et al. (1983).
Danziger and de Velloso (1995) proposed a correlation between CPT and SPT for some
Brazilian soils. Values found were in the same range obtained by Schmertmann (1970).
Different types of correlation were tested, and a linear correlation was found better suited forpractical applications. A general trend was obtained in a similar pattern of Robertson’s curve(increasing n-values with increasing grain size).
Lunne et al. (1997) cited Jefferies and Davies (1993) who presented a soil classification chart
estimating N-values. This new development considers qc by taking into account pore waterpressure (u) and overburden stress, using piezocone.
Akca (2003) proposed SPT-CPT correlation for United Arab Emirates Soils. Results of his
study showed higher values of n = qc/N60 when compared to values found in the literature.
He explained that higher values are due to cementation, densification and Shelly structure or
gravel layers in the United Arab Emirates soils.
127

McNulty & Harney (2010) have compared effective angle of internal friction estimated fromthe CPT with those determined from SPT N-values and laboratory triaxial tests. Their study
revealed that effective angle of internal friction obtained from triaxial tests correlated wellwith those obtained from the CPT and SPT below the water table, but above the ground waterobtained values from CPT and SPT were significantly high compared to laboratory
measurement.
Research by Elbanna et al. (2011) suggested that, in the absence of site specific CPT-SPT
correlations, it is suitable to use the general correlation proposed by Robertson, et al (1983).
In the absence of grain size data, they have also proposed a new correlation using the qt/(N)60
ratio of 0.45. However, some of the existing correlations provide best estimated relationshipbetween qc and N-value, but region specific study result presented by Elkateb and Ali (2010)
represents quite inapplicability of existing correlations. Therefore, direct application of theaverage relationship presented in several correlations may lead to significant deviation fromexact result.
Shahri et al. (2014) proposed a correlation between qc and N-value for various soil layers,
particularly in clayey soils with significant clay content in an area in southwest Sweden. They
proposed linear and power relationships to predict qc using N-value. The results of their study
showed a good agreement with previous work by other researchers.
Tarawneh (2014) developed a multiple linear regression (MLR) and a symbolic regression(SR) models to predict N-value using CPT data for sand, sandy silt, and silty sand soils.
Asci et al. (2015) proposed exponential models to predict CPT qc value from SPT N-values
for silty clay, clayey silt, clay, and sandy silt.

4

OBJECTIVE OF THE RESEARCH

The primary objective of this research is
1. To examine the applicability of various existing CPT-SPT correlations for Uttara 3rd phasesoils
2. To propose possible new correlations
3. To provide useful contribution for further improvement of region specific CPT-SPT
correlations.

128

6

FIELD INVESTIGATION

By the appliance of cone penetration testing (CPT) and standard penetration
testing (SPT) field investigations were carried out mostly. Six pairs of CPT and
SPT were performed in different locations within the study area. In this research,
field investigations were carried out in Uttara Residential Model Town (3rd
Phase), Dhaka , Bangladesh in which each pair of CPT and SPT was carried out as
close as possible and the horizontal distance was not greater than 1m. A map of
Uttara Residential Model Town (3rd phase) is shown in Figure 6.1.

Figure 6.1. Study location (Uttara 3rd Phase)
The subsoil profile at study area can be divided into three strata based on the results of thesubsurface explorations. The soil within the test area is largely comprised of fine sand and silt
clay particles. The top layer consists of light grey to grey medium to loose fine sand tracemica with a total thickness approximately 4.75 m to 7.5 m. Directly below this layer, a layerof dark grey silty clay with organic matter is situated to a depth varied from 7.65 m to 9.45 m.
The bottom layer consists of high plastic grey medium stiff clay or medium plastic soft tomedium stiff clay upto the depth of 10.35 m. Ground water table is located at 2.3-2.7 m
below from EGL.
6 boreholes were investigated from which section profile of Bore Hole 16-6 is shown infigure 6.2 and 6.3.

Figure 6.2 Cross sectional profile along X-axis of BH-16-6

Figure 6.3 Cross sectional profile along Y-axis of BH-16-6

130

The corrected tip resistance (qt), corrected SPT value (N1)60 values are presented in Figure
6.4
Site 2-BH-10

Site 13-BH-6

0

N1,60
20

Site 16-BH-6

N1,60

N1,60
qc1

0

40

0

0

2

2

4

N1,60

20

40

20

30

40

0

4

4

6

8

Depth (m)Depth (m)Depth (m)

10

2

6
6
8

8

10

10
10

12

12

12

14

14

14

16
0

0

1

2

qc1 (Mpa)

16
0

3

1

2

3

0

4

qc1(Mpa)

Site 17-BH-11

Site 24-BH-7

N1,60
20

N1,60
20

Site 42-BH-9

0

40

10

30

0

2

2

2

4

4

4

6

6

6

Depth (m)

0

8

8

12

12

12

14

14

14

16
3

20

30

10

10

1
2
qc1(Mpa)

10

8

10

16

6

N1,60

0

40

0

0

2

qc1 (Mpa)

Depth (m)Depth (m)

0

16
0

1
2
qc1 (Mpa)

3

0

0.5

1
1.5
qc1 (Mpa)

2

Figure 6.4. Depth versus corrected cone tip resistance (qt), SPT N60 and (N1)60 values forall borehole131

Note that, there was considerable variability in the measured SPT N-value indifferent
boreholes at different depths ranging from 2 to 18 and maximum corrected cone tip resistance(qt) was close to 4 MPa consistency of the soils at different depth varies from stiff to loose.

Cone Penetration Test
The cone penetration or cone penetrometer test (CPT) is a method used to determine
the geotechnical engineering properties of soils and delineating soil stratigraphy. It was
initially developed in the 1950s at the Dutch Laboratory for Soil Mechanics in Delft toinvestigate soft soils. Based on this history it has also been called the "Dutch cone test".
Today, the CPT is one of the most used and accepted soil methods for soil
investigation worldwide. In procedure Cone penetration testing two parameters is usuallytaken into account. One is pre- drilling and the other is verticality. In our test procedure a
Hogentogler type piezocone penetrometer with a cross sectional area of 10 cm2 was used as
pre-drilling which can measure the pore water pressure (u2), as well as the cone tip resistance(qc) and sleeve friction(fs). In order to perform the test correctly the thrust machine should be
set up vertically. The deviation of the initial thrust direction from vertical should not exceed 2
degrees and push rods should be checked for straightness. In our test procedure the cone waspushed vertically into the ground at a constant rate of approximately 11-12.5m/min. During
the procedure, measurements of dynamic pore water pressure, tip resistance and sleeve
friction were recorded continuously at 10 mm depth increments. The typical penetration
depth for this study was approximately 12-14 m below from ground surface. For soil
exploration, a modern and expedient approach is offered by cone penetration testing (CPT)
which involves pushing an instrumented electronic penetrometer into the soil and recording
multiple measurements continuously with depth (e.g., Schmertmann, 1978; Campanella &Robertson, 1988; Briaud & Miran, 1992). Per ASTM and international standards, three
separate measurements of tip resistance (qc ), sleeve friction (fs), and porewater pressure (u)are obtained with depth as depicted in figure 6.5

132Figure 6.5. Overview of the Cone Penetration Test (CPT) Per ASTM D 5778
Procedures.
According to this we also obtained a relationship of Cone Resistance (qt), Sleeve friction (fs)and Pore pressure (u2) with Depth for the six bore holes. They are given below in figure 3.7.

0

BH
2-10

2

0

500

0

0

0

0

2

2

2

4

4

4

6

6

6

8

8

8

10

10

10

12

12

12

14

14

14

16

16

16

100

0

1

2

0
2
4

500
0

4

2

100

0

50

100

8

8

12
14

10

10

12

12

14

14
16

16

16

0

0

500

0

0

0

2

2

2

4

4

4

6

6

6

8

8

8

10

10

10

12

12

12

14

14

14

16

16

16

0

BH
1711

50

6
8

10

BH
16-6

0

4

6

6

BH
13-6

0
2

1

0

2

50

0

0

0

0

2

2

2

4

4

4

6

6

6

8

8

8

10

10

10

12

12

12

14

14

14

16

16

16

100

0

BH
247

2

0

500

0

0

2

2

2

4

4

4

6

6

6

8

8

8

10

10

10

12

12

12

14

14

14

16

16

16

0

BH
429

1

0

1

2

0

500

0

0

0

2

2

2

4

4

4

6

6

6

8

8

8

10

10

10

12

12

12

14

14

14

16

16

16

0

100

0

100

Figure 6.6. Representative Soil profile for Cone resistance, Pore Pressure and friction
ratio along Depth for Uttara 3rd phase

7 Laboratory Test
The sand samples recovered in the sampler during the Standard Penetration Tests were used
for laboratory test for determination of grain size distribution, unit weight relative density andeffective friction angle.

Sieve Analysis
A Sieve analysis is a practice or procedure used to assess the particle size distributionof a granular material.Sieve analysis was performed on each soil sample according to
ASTM C136. Soil samples which were recovered from six bore holes were individuallyassessed and classified based on dry sieve analysis for sieve analysis testing.These soils
contained significant amounts of fines (fc) which ranged from 2.3 to 96.4. Finenessmodulus is an empirical figure which was obtained by adding the total percentage of thesample of an aggregate retained on each of a specified series of sieves, and dividing thesum by 100. Range of fineness modulus was 0.02 to 1.02 and mean grain size (d50) was
ranging from 0.12 to 0.19.Based on the sieve analysis results, the soils are generallyclassified into two groups; Well graded sands with little silt and Poorly graded sandswith silt. According to the unified soil classification system, the soils can be symbolized
as SW and SP-SM, respectively. The mean grain size (d50), percent finer than 0.074 mm(fc) and fineness modulus (F.M) for six boreholes are given in table 3.2.
Table 7.1. Grain Size Distribution
Depthbore hole 2-10

borehole 13-16

borehole 16-6

borehole 17-11

borehole 24-7

borehole 42-9

m

d50

fc

F.M.

d50

fc

F.M.

d50

fc

F.M.

d50

fc

F.M.

d50

fc

F.M.

d50

fc

F.M.

0.45

0.14

5.3

0.4

0.15

10

0.6

0.17

7.1

0.67

0.15

4.8

0.6

0.2

5.6

0.72

0.16

14

0.57

0.9

0.14

10

0.51

0.16

8.1

0.6

0.18

12.7

0.78

0.17

3.4

0.7

0.2

5.6

0.72

0.16

15

0.58

1.35

0.14

7.3

0.49

0.16

8.8

0.6

0.17

13.3

0.68

0.17

6

0.7

0.2

4.1

0.79

0.14

15

0.47

1.8

0.14

10

0.5

0.17

8.6

0.7

0.17

9.8

0.7

0.16

8.6

0.6

0.2

3.4

0.77

0.15

9.5

0.53

2.25

0.14

6.8

0.49

0.19

5.6

0.8

0.15

14.6

0.56

0.17

10

0.7

0.2

3.7

0.78

0.14

7.1

0.47

2.7

0.15

7.2

0.54

0.18

6.9

0.8

0.14

18.4

0.51

0.17

9.9

0.6

0.2

2.9

0.8

0.14

16

0.48

3.15

0.14

7

0.48

0.18

7.1

0.8

0.13

17.4

0.44

0.17

9.8

0.7

0.2

3.4

0.79

0.14

9.2

0.51

3.6

0.15

4.2

0.52

0.19

7.6

0.8

0.14

16.6

0.48

0.17

8

0.6

0.2

3.4

0.79

0.14

8.2

0.49

4.05

0.15

6.3

0.51

0.18

6.8

0.8

0.15

15.2

0.6

0.17

8.2

0.6

0.2

3.9

0.79

0.15

7.1

0.54

4.5

0.15

3.1

0.55

0.19

6.4

0.8

0.14

19.9

0.49

0.16

8.9

0.6

0.2

7.2

0.71

0.16

16

0.57

4.95

0.14

8.1

0.45

0.18

6

0.7

0.17

8.7

0.7

0.17

8.6

0.6

0.2

3.6

0.8

ND*

53

1

5.4

0.17

10

0.4

0.18

6.9

0.8

0.17

6.3

0.63

0.15

11

0.6

0.2

3.4

0.79

ND*

79

0.15

5.85

0.12

2.3

0.62

0.18

6.8

0.8

0.17

5.3

0.64

0.13

14

0.4

0.2

3.9

0.78

ND*

79

0.15

6.3

ND*

13

0.35

ND*

29

0.9

ND*

8.3

0.34

ND*

53

1

0.2

4

0.79

ND*

79

0.15

6.75

ND*

91

0.06

ND*

29

0.3

ND*

69.1

0.69

ND*

96

0

0.2

11

0.75

ND*

79

0.15

7.2

ND*

ND*

ND*

ND*

ND*

ND*

ND*

ND*

ND*

ND*

96

0

0.2

8.8

0.65

ND*

79

0.15

ND*=Not-Determined
d50 in mm

136

Relative Density Test
Relative density or density index is the ratio of the difference between the void ratios of acohesion less soil in its loosest state and existing natural state to the difference between its
void ratio in the loosest and densest states. Porosity of a soil depends on the shape of grain,
uniformity of grain size and condition of sedimentation. Hence porosity itself does notindicate whether a soil is in loose or dense state. This information can only be obtained bycomparing the porosity or void ratio of the given soil with that of the same soil in its loosest
and densest possible state and hence the term, relative density is introduced.
According to ASTM D2167 Relative Density Test was done which was done which is
described below.

Calibration of mould :1. At first the inside diameter of mould was measured at different depths using a bore gauge
and the average was taken.
2. Then the mould on a flat surface or flat plate was kept. The height at different positions
was measured and the average was taken. (accuracy = 0.025 mm).
3. For loose state soil sample was poured in the container and the weight was taken.
4. For Dense state soil sample was poured in three layers by tamping two times in which theblowing was done 25 times each.

Figure 7.1. Pouring soil sample in the container.

137

Minimum Density:
The mould was weighed accurately (W). The dry pulverized soil into the mould was poured
through a funnel in a steady stream. The spout was adjusted so that the free fall of soil
particle was always 25 mm. While pouring soil the spout must have a spiral motion from therim to the centre. The process was continued to fill up the mold with soil upto about 25mm
above the top. It was then leveled, with the soil and weight was recorded (W1).

Maximum Density:
The empty mould (W) was weighted. The collar on top of the mould was put and it was
clamped. The mould was filled with the oven dried soil sample till 1 / 2or 2 / 3of the collar isfilled. The mould was placed on the vibrating deck and fix it with nuts and bolts. Then thesurcharge weight was on it. The vibrator was allowed to run for 8 minutes. Then mould wasweighed with the soil and weight is recorded (W2).

Natural Density:
The mould with dry soil was weighted. Knowing the volume of the mould and weight of dry
soil natural density can be calculated.

Direct Shear Test
A direct shear test is a laboratory or field test used by geotechnical engineers to measure
the shear strength properties of soil or rock material, or of discontinuities in soil or rockmasses.

138

The Test has been conducted according to ASTM.
1. At first the inner dimension of the soil container has been checked.
2. Then the parts of the soil container have been put together.
3. After that the volume of the container has been calculated and the container has been
weighted.
4. At first the soil was placed in loose state. Then it was placed in medium dense state bytamping 1 time by 40 blows. After that the soil sample was placed in dense state by tamping
2 times in which number of blow was around 40 each time.
5.Then the soil container was weighted, the difference of these two is the weight of the soil. It
was observed that in loose state, weight of soil was around 100-110 gm. In medium dense
state the weight was between 110-120 gm. And in dense state the weight of soil was morethan 120 gm. Then the density of the soil has been calculated.
6. For the purpose of the test the surface of the soil was made plane.
7. Then the upper grating was put on stone and loading block was put on top of soil.
8. After that the thickness of soil specimen was measured and it was one inch.
9. Then load of 5 kg, 10 kg and 20 kg were applied for each bore hole for three different
states that was loose, medium dense and dense.
10. Removing the shear pin was a must.
11. Then the dial gauge was attached which measured the change of volume.
12.After that the initial reading of the dial gauge was recorded and calibration values was also
recorded.

Figure 7.2. Equipment of Direct Shear Test.

139

13. Before proceeding to test all adjustments were checked to see that there is no connection
between two parts except sand.
14. Then the motor was started. The reading of the shear force was taken and the reading wasrecorded also. The dial gauges was set to zero, before starting the experiment.
Thus, Test program and procedure of Sieve Analysis Test, Relative Density Test and Direct
Shear Test as well as relevant images of equipment has been discussed in this chapter.

8

TEST RESULT, COMPARISON AND DISCUSSION

This chapter contains the interpretation of the establishment of correlations of a suite of
geotechnical engineering parameters with the measured data from CPTu and SPT by using avariety of theoretical, analytical and statistical methods. The soil parameters those areincluded in this study are mean grain size(D50), fines content (fc), unit weight (), relative
density (Dr), effective friction angle (φ′). Correlations are established through multiple
regression analysis which may be used for further study for the local soil of Bangladesh.

Cone Penetration Test
Vertical readings of cone tip resistance (qt) and sleeve friction (fs) are used either separately
or together to evaluate soil engineering parameters. The tip resistance is corrected (qc) for
pore water effects on the back of the cone tip (Lunne et al., 1997). A calibration factor of 0.32
is used to perform the calibrations on recorded cone tip resistance data as provided by thecone manufacturer to get corrected cone tip resistance qc. Furthermore, the cone tip resistance
was normalized (qt1) to an overburden stress level of 100 kPa.

Standard Penetration Test
The relationships between corrected SPT number (N1)60 and soil parameters have been
discussed to make sure the applicability of this relations for local soil. Corrected SPT number(N1)60 is obtained by The SPT energy corrections and overburden pressure corrections
applied to the recorded field N-values based on field SPT N values soil is profiled into
medium dense(N=10-30),loose(N=4-10) and very loose(N 4).

140

Laboratory Tests
Results from sieve analysis, relative density test and direct shear test are used to obtain the
CPT-SPT based correlations for soils of a selected area of Uttara, Dhaka city.
From the subsurface explorations it was observed that the soil within the test area is primarily
comprised of fine sand and silt clay particles. The sand layer contain appreciable amounts offines (fc) ranging from 2.3 to 96.4, fineness modulus (an empirical figure obtained by adding
the total percentage of the sample of an aggregate retained on each of a specified series ofsieves, and dividing the sum by 100) ranging from 0.02 to 1.02 and mean grain size (D50)
ranging from 0.12 to 0.19. Based on the sieve analysis results, the soils are generallyclassified into two groups: - either well graded sands with little silt or poorly graded sandswith silt.
Results obtained from the relative density shows that the average density of sand for loosest
sate is ranged between 12.31 KN/m3-12.91 KN/m3 whereas average density for densest stateranging from 15.5 KN/m3-16.6 KN/m3.Field density was about the average of density of
maximum and minimum sate.
Effective friction angle for the sand layer has been determined for very loose, loose andmedium dense condition from direct shear test. Shear stress vs normal stress graph for thesands of five boreholes for very loose, loose and medium dense state shows a small amountof cohesion are present though the test has been conducted for sandy layer because the layerof sand was not pure, silt was considerably present in sand.

Statistical Analysis:
To determine the correlation between CPT and SPT and soil parameters we executed astatistical analysis. This analysis was performed in various states including all obtained data
and filtered data. The filtering procedure which is defined as
and

2σ (

is mean value of ‘n’

is the standard deviation of the mean value of n were disregarded by using 95% of thedata is still allowed in the investigation range) aimed to remove data situated far from thegeneral trend. After data filtering and elimination, the same trend should be confirmed to be
maintained in plot. Then, to determine the correlation functions using the least square
method, linear and power regression were implemented.

141

CPT-SPT based correlations:
Mean Grain Size (D50)
Correlations based on Mean grain size (D50) and qc/N60 illustrated by Robertson et al. fornorth American soil (1983), Burland and Burbidge for London soils (1985), Kulhawy &Mayne for soils of California (1990), Canadian foundation engineering manual (Canadian
Geotechnical Society 1992) and Anagnostopoulos for Greek soils (2003) are shown in Figure
4.1.The data sets selected for this study are then plotted on the same figure to evaluate theapplicability of these correlations to the local soils. Results of CPT readings are averaged
over 0.45m intervals for cone tip resistance values and compared with the SPT N-value
situated over the same depth range. When choosing the level, the first thing considered was
the depth of the SPT blow count accomplished. Then, the cone resistance values wereaveraged over 0.45 m at the same level. A total of 75 data points for the sand deposits fromthe 6 boreholes presented in Table 1were selected for this study to perform comparative
analysis with mean grain size (D50).
qc/N60 ratio of selected data set are less scattered and varies from 1-11 for a variation of D50
from .14-.19 mm and surprisingly 71.4% of the data fall within the range of existing corelationships The upper and lower range for study soil was provided using regression
analysis. Linear correlation with zero intercept is preferred although the linear correlation
with intercept and power correlation also give the acceptable range of correlation coefficient.

142

18
16
14

(qc/pa)/N60

12
10
8
6
4
2
0
0.001

0.01

D50

BH 2‐10
BH 16‐6
BH 24‐7
Burland and Burbidge upper (1985)
Robertson lower (1990)
Kulhawy and Mayne (1990)
Anagnostopoulos et al (2003)

0.1

1

BH 13‐6
BH 17‐11
BH 42‐9
Burland and Burbidge upper lower (1985)
Robertson upper (1990)
CFEM (1992)
Proposed Lower

Figure 8.1. Variation of ratio (qc/pa)/N60 with mean grain size, D50 comparison
The proposed upper range nearly coincides with the upper range of Robertson et al.
Proposed Upper :

⁄

⁄

10 ∗

Proposed Lower

⁄

⁄

1.5 ∗

.
.

Percent of fine content
The fine content based correlations proposed by Jamiolkowski(1986) for undisturbed soil,
Chin et al. (1988) and Kulhawy & Mayne (1990) for dubai soil are presented in Figure 8.2
along with collected data sets of this study.

143

8

7

6

(qc/pa)/N60

5

4

3

2

1

0
0

10

20

30

40

50

60

70

80

90

100

Fines Content ,f (%)

c
BH 2‐10
BH 13‐6
BH 16‐6
BH 17‐11
BH 24‐7
BH 42‐9
Jamiolkowski et al. (1985)
Chin et al. (1988)
Kulhawy and Mayne (1990)
Proposed Lower ( (qc/pa)/N60=0.36552‐0.00247*Fc)
Proposed Upper (=2.8‐0.016*Fc )Figure 8.2.Variation of ratio (qc/pa)/N60 with fine content (fc) comparison
But, from the plotted data it can be noted that the amount of fines content for the soil of
Uttara 3rd phase is ranged mainly between 2-20 %. The upper and lower range for study soil
was provided using regression analysis, linear correlation with intercept. Proposed upper
range (for qc/N≥3) (qc/pa)/N60=2.8-0.016*fc, the qc/N ratio decreased with increasing finecontent which is somewhat similar to the existing correlations but for the proposed lower
range for qc/N<3 (qc/pa)/N60=0.365-0.00247*fc, the qc/N ratio increased with increasing finecontent.

144

Unit weight ()A direct unit weight relationship with the CTP sleeve friction proposed by Mayne and Peuchen(2012) is presented in Figure 4.3. where the specific units include:  (kN/m3) and fs (kPa). A simpler
expression is also represented in Fig 2 by Mayne (2014) for the sandy soil of the eastern suburbs of
New Orleans.
The data sets selected for this study are then plotted on the same figure to evaluate the applicabilityof these correlations to the local soils. Results of CPT readings for five boreholes are averaged overthe sand layer for sleeve friction values .5 data point is achieved for unit weight by Laboratory
Investigation for comparison with sleeve friction. it is evident that 60% of the data are less scatteredand falls in the existing correlation
28
26

Unit Weight,(KN/m3)

24
22
20

r2=0.878

18
16
14
12
0.1

1

10

100

1000

10000

CPT Sleeve Friction Resistance(fs)BH 2‐10
BH 17‐11
BH 42‐9Mayne Simplified (2014)

BH 13‐6
BH 24‐7
Mayne and Peuchen (2012)
Proposed

Figure 8.3. Trend of soil unit weight with CPT sleeve friction reading.
So, based on existing correlation regression analysis is done and new correlation is proposed forwhich coefficient of correlation is quite satisfactory(r2=.878).
Proposed Correlation: 

11.54285

1.236825 ∗ ln

(r2=0.848)

145

Relative Density(Dr)Correlation based on relative density with SPT (N1)60 values given by Terzaghi and Peck (1948) for
undisturbed sandy soil is illustrated in Fig.4.4. To make the comparison with existing correlation
with the results from SPT blow count and relative density test is also plotted in the same Fig.
Relative density of a respective borehole is plotted against the average (N1)60 values for the wholesand layer.
Figure 8.4 indicates that actual values of Dr for the sand of Uttara 3rd phase are higher than thevalues predicted from the existing correlation. So, a new equation is needed for

determining Drrdfrom SPT (N1)60 for the soil of Uttara 3 phase.
90

Relative Density,Dr(%)

80
70
60

r2=0.5791

50
40
30
20
10
0
0

1

2

3

4

5

6

7

8

SPT (N1)60 VALUE
BH 2‐10

BH 13‐6

BH 17‐11

BH 24‐7

BH 42‐9

Terzaghi & Peck (1948)

Proposed (Dr=100*.12689*√(N1)60 )Figure 8.4.Relative Density of sands from Standard Penetration Test Data.
The proposed correlation : D

100 ∗ 0.12689√ N(r2=0.5791)

Relation expressed by Robertson and Campanella (1983) for normally-consolidated clean
quartz sands are illustrated in Figure 4.5. Results from CPT and laboratory relative density
test of sand of respective boreholes are plotted in same Fig and are used to compare with theexisting correlation. Values of normalized cone tip resistance are averaged for the sand layer
for a certain borehole.

146

80

Relative Density,Dr(%)

70
r2=0.519

60
50
40
30
20
10
0
0

4

8

12

Normalized Cone Tip Resistance(qt1)
BH 2‐10

BH 13‐6

Bh 17‐11

BH 24‐7

BH 42‐9Robertson and Campanella(1983)

Proposed, Dr=100*0.249*(SQRT(qt1))

Figure 8.5.Relative Density Evaluations of NC sands from normalized cone tip resistance
All set of data from relative density test have fallen in the higher range than predicted value
from correlation given by Robertson and Campanella(1983). So, a new correlation isestablished by regression analysis in by following the same trend for which coefficient ofcorrelation is quite satisfactory.
100 ∗ 0.249√

Proposed correlation:(r2=0.519)

Effective Friction Angle(φ′)
Correlations based on effective friction angle and SPT (N1)60 values illustrated by Hatanaka and
Uchida (1996) for Japanese soil (1983) and specification for highway bridge shown in Figure 4.6.
Result from SPT are plotted in the same Fig to compare the relationship with Friction angle for veryloose, loose and Medium Dense condition. While taking (N1)60for these three condition averageof(N1)60values are taken for certain layer for 5 boreholes. For Bore Hole 24/7 and 42/9 there is nolayer of medium Dense sand and for BH 13/6there is no layer of very loose sand. So, those data point
areeliminatedfromplotting

andcomparing

withexisting

correlations.

From the relationship between effective friction angle, φ′ and corrected standard penetration blow
number for sands the effective friction angle for very loose state <30 for loose sate 30-35, for
medium Dense 35-40( Meyerhof 1956,Foundation Engineering Handbook).Almost same relationshipgiven by Peck (1974) and Bowels (1971)

Figure 4.6 shows that though for very loose sate effective friction angle is little higher; for loose andmedium dense state values of friction angle follows the range given by Meherhoff (1956) It is also
evident that for each density sate, values of effective friction angle are higher than the proposed
Hatanaka and Uchida(1996) and specifications for highway bridge.
25.4749

For Very Loose:
For Loose:

29.23022.

2.03656 ∗29.47

For medium Dense:.

4.89816 ∗(r2=0.37)(r2=0.442).

5.66584 ∗(r2=0.319)

40
r2=.319

Effective Friction Angle,′35
r2=0.442

r2=0.37

30
25
20
15
10
5
0
0

1

2

3

4

5

6

7

8

9

10

SPT (N1)60
Very Loose

Loose

Medium Dense

Hatanaka & Uchida (1996)

Specifications for high way bridges: N≧5)

Proposed for Very Loose

Proposed For Loose

Proposed for Medium Dense

Figure 8.6. Peak friction angle of sands from SPT data
The expression derived by Kulhawy & Mayne (1990) for soil of California for quartz-silica sands,
Robertson and Campanella(1983) for Okland soil and Uzeilli et al (2013) to correlate effective
friction angle with normalized cone tip resistance are illustrated in Figure. 4.7.Result obtained fromdirect shear test for three different density state for five boreholes and from CPT are also plotted in
the same Fig to compare with the reference expressions. Results from CPT for cohesionless layer are
averaged for very loose, loose and Medium Dense sands.

Figure 4.7 Shows that value of Effective Friction for all density condition for normalized Cone tip
resistance are higher than values obtained from predicted correlation for effective friction angle,
which explains the necessity for new correlation for local soil.
40
r2=0.363
r2=0.574
r2=0.451

Effective Friction Angle (′)

35
30
25
20
15
10
5
0
0

2

4

6

8

10

12

14

16

18

20

Normalized Cone Tip Resistance(qt1)
Very Loose
Loose
Medium Dense
Robertson and Capanella(1983)
Kulhaway and Mayne(1990)
Uzielli et al(2013)
Proposed for Very Loose(φ′=29.68812+2.4084*(qt1))
Proposed for Loose(φ′=30.42829+2.519*LOG(qt1))
Proposed for Medium Dense(φ′=29.2175+5.62161*LOG(qt1))

Figure 8.7. Direct relationships between peak friction angle and normalized cone resistanceMultiple regression analysis is performed in the similar way to obtain new correlation for effective
friction angle with cone tip resistance as test results are following almost same trend line andcoefficient of correlation obtained is quite satisfactory.
29.68812

For Very loose :For Loose:

30.42829

For Medium dense:

2.4084 ∗ log

2.519 ∗ log

29.2175(r2=0.451)(r2=0.574)

5.62161 ∗ log(r2=0.363)

Correlation for cone tip resistance and SPT blow
16
14
12

qt(Mpa)

10
8
6
4
2
0
0

2

4

6

8

10

12

14

16

Corrected SPT blow,(N1)60
De Alencar (1998)

Elbanna et al (2011)

Proposed Relationship for Local Soil

BH 2‐10

BH 13‐6

BH 16‐6

BH 17‐11

BH 24‐7

BH 42‐9Figure 8.8. Variation of normalized cone tip resistance (qt) with normalized SPT blow countFig. 8.8 compares the measured data with the single value of qt/(N1)60 ratio of 0.45 suggested by de
Alancer (1995) Elbanna et al. (2011).
The plotted data shows surprisingly are within the range of values with the average value of 0.45
though the study soil was not pure sand, but they show a similar linear relationship and nearly
maintains a qt/(N1)60ratio of 0.35. It is believed that the proposed correlation between normalized
cone tip resistance and normalized SPT (N1)60 can serve as a better relationship for the local soils.
The main advantage of this relationship is that it can be used in the absence of gradation results.
Therefore, it is a need to collect additional high quality CPT and SPT data to develop a better
relationship.

9

CONCLUSIONSThis research has assessed the correlation based on CPT and SPT for Dhaka sand from the selected
area. The existing SPT-CPT correlations were reviewed considering:a) the historical evolution of the need for SPT-CPT correlations,b) the factors that influence the correlation;
150c) sources of scatter in the correlations, andd) the existing correlations
Based on data from laboratory investigation of undisturbed samples and measured SPT and CPT
resistance, an empirical correlation between the SPT blow count and CPT cone tip resistance andsleeve friction of sandy soils is established. The results obtainedin the research work issummarized below :It has been observed that rather than available relationships between qc/N60 and Fine content forcohesionlesssoil, the developed correlations for qc/N60 with D50 show good applicability to local
soils. New correlation ranges to (qc/pa)/N60=10*D50^0.25 to (qc/pa)/N60=1.5*D50^0.3and (qc/pa)/N60 =2.8-0.0016*fc (for qc/N60≥3) and (qc/pa)/N60 =0.36552-.00247*fc (for qc/N60< 3) have been proposed.

Compared with the correlation for unit weight with CPT sleeve friction given by Mayne
and Peuchen (2012) and the simplified correlation by Mayne (2014) , a new correlation
developed for local sand. In the developed relationship the unit weight is increasing by afactor of 2.3 (10 kN/m3≤ ≤ 23 kN/m3) while the sleeve friction is spanning three orders ofmagnitude (0.5kPa ≤ fs ≤ 1000 kPa), thus an accurate fs is not necessary given that the expectedvariance is on the order of ± 1.236kN/m3in the estimated value of unit weight.

Correlation for relative density with SPT blow count and CPT normalized cone tip
resistance is established separately. The determined relation between relative density withcorrected SPT (N1)60 values ,100 ∗ 0.12689 ∗ √matches better than the existing

relation expressed by Terzaghi and Peck (1948) for local sands. In case of correlation
between relative density with normalized cone tip resistance , rather than the existingcorrelationbyRobertson

100 ∗ 0.249 ∗andCampanella(1983)

thedetermined

relationshipfits better with a quite satisfactory correlation coefficient.

Separate correlations are also developed for CPT and SPT with effective friction angle.
Values of effective friction angle for loose and medium dense state are matchedsatisfactorily within the range of values for effective friction angle given by
Mayerhoff(1956) and Peck (1974) while the values for very loose state are deviated from therange. Thus, a set of new correlations are developed for effective friction angle using CPT
and SPT data separately for each of density state of sand from Uttara 3rd phase.
A correlation is also established between CPT qc and SPT N60for sandy soil of the selected151

area in which the CPT and SPT data used for this study better suit with (qt/(N1)60) ratio of0.35 instead of 0.45 proposed by Elbanna (2011).
Results that are found from the statistical approach give almost similar results withliterature value. Using regression analysis correlations are developed for which higher
correlation coefficient is obtained.



Generally speaking, available established correlations provide a good framework to start
with, but the direct application of the average curve in engineering practice may lead todeviation, so proper relationships should be developed for local soils. Unfortunately, theavailable data sets which exist for the study area falls within a relatively narrow range fordeveloping good correlations. It is needed to further investigate by accumulating large
amount of high quality data from various sands from different places.

References


Agaiby S, Abdel-Rahman A, Ahmed S, Baghdady A. qc/N Ratiofor recently depositedcrushable soils. In: Singapore, Phoon K,Chua T, Yang H, Cham W, editors. International
symposium onadvances in foundation engineering (ISAFE 2013) 5–6 December2013; inpress.



Ahmed S.M, Agaiby S.W, Abdel-Rahman A.H. (2013) , A unified CPT–SPT correlation for
non-crushable and crushable cohesionless soilsGeotechnical Engineering, Ain Shams
University, Cairo, Egypt, Geotechnical & Heavy Civil Eng Dept.,Dar Al-Handasah (Shair
and Partners), Cairo, Egypt,Geotechnical Engineering, National Research Center, Cairo,
Egypt.



Akca N. Correlation of SPT–CPT data from the United ArabEmirates. Eng Geol
2003;67:219–31.

Anagpstopoulos M, Jamiolkowski M, Peterson R. Preliminary result of CPT tests incalcareous Quiou sand. In: Proceedings of theinternational symposium on calibrationchamber testing, Potsdam, New York; 2003. p. 41–53

Banglapedia, National Encyclopedia of BangladeshBurland R, Burbidige S, Fretti C, Ghionna VN, Pedroni S. Compressibility andcrushability ofsands at high stresses. In: Proceedings of theinternational symposium on calibration chamber
testing, Potsdam, New York; 1985. p. 79–90.

152



Chin C, Duann S, Kao T. SPT–CPT correlations for granular soils. In: Proceedings of the 1st
international symposium on penetration testing (ISOPT-1), vol. 1; 1988. p. 335–9.



CPT guide 2015 by GREGG

Cubrinovski M., Ishihara K.( 2014) Correlation between penetration resistance and relative
density of sandy soils, Science University of Tokyo, Tokyo, Japan

De Alencer F, Politano C, Danziger B, Robertson P, Mayne P.CPT–SPT correlations forsome Brazilian residual soils. In:Geotechnical site characterization, Proceedings of thefirstinternational conference on site characterization-ISC’98 vol. 2. Atlanta, Georgia, USA,AA Balkema; 1998. p.907–12.

Elbanna T.M.,Ain Shams University, Cairo, Egypt/ Sogreah Gulf, Dubai, UAE, Ali H.E,
AinShams University, Cairo, Egypt/ COWI, Dubai, UAE (2011) CPT-SPT correlations forcalcareous sand in the PersianGulf area.

Elkateb T, Ali H. CPT–SPT correlations for calcareous sand inthe Persian Gulf area. In: 2nd
International symposium on conepenetration testing, 9–11, California, USA; 2010.



Hatanaka O, Uchida M. Japan 1996, Analysis for correlation of SPT and other geotechnicalparameters for soil of Japan.



Jefferies M, Davies M. Use of CPTU to estimate equivalent SPTN60. Geotech Test J ASTM
1993;16(4):458–68.

Kara O, Gu¨ ndu¨ z Z. Correlation between CPT and SPT inAdapazari, Turkey. In:
International symposium on cone penetration testing, 9–11, California, USA; 2010.



Kulhawy F, Mayne P. Manual on estimating soil properties forfoundation design. Report no.
EPRI-EL-6800, Electric PowerResearch Institute, EPRI; 1990.



Lambe T.W, Soil Testing for Engineers (1951)



Lee J, Guimaraes M, Santamarina J. Micaceous sands: microscalemechanisms andmacroscale response. ASCE J Geotech Geoenviron Eng 2007;133(9):1136–43.

Lunne T, Robertson P, Powell J. Cone penetration testing ingeotechnical practice. New York
(USA): Blackie Academic, EFSpon/Routledge Publ; 1997.



Mayne, P.W. (2014). KN2: Interpretation of geotechnical parameters from seismic piezocone
tests.Proceedings, 3rd International Symposium on Cone PenetrationTesting(CPT'14, Las
Vegas), ISSMGETechnical Committee TC 102, Edited by P.K. Robertson and K.I. Cabal: p 47-73.

Mominul H.M, Ansary M.A, Abedin M.J. (2016) Applicability of existing CPT, SPT and soil
parameter correlations for Bangladesh,Bangladesh University of Engineering andTechnology, Dhaka, Bangladesh

153



Moore C. Effect of mica on K0 compressibility of two soils. ASCEJ Soil Mech Found Eng
Div 1971;97(SM9):1251–91.

Ozan C. Estimation of grain characteristics of soils by using conepenetration test (CPT) data.
M.Sc. Thesis, The Dept. of CivilEngineering, The Middle East Technical University,
Turkey;2003. 60p.

Paul W. Mayne, (2007),Cone Penetration Testing State-of-PracticePeck R.B, Hanson W.E, Thornburn T.H, Foundation Engineering (2nd edition, 1974)

Robertson P. In-situ testing of soil with emphasis on itsapplication to liquefaction assessment.
Ph.D.

thesis.

Departmentof

Civil

Engineering,

UniversityofBritishColumbia,

Vancouver,Canada; 1982. 395p.
Robertson P. Interpretation of in-situ tests – some insights.Mitchell Lecture-ISC’4 Brazil;
2012.



Robertson P, Campanella R, Wightman A. SPT-CPT correlations. ASCE J Geotech Eng
1983;109(11):1449–59.

Robertson P, Cabal K. Guide to cone penetration testing forgeotechnical engineering, 5th ed.
Gregg Drilling & Testing; 2012.



Robertson P. Soil classification using the cone penetration test.Can Geotech J
1990;27(1):151–8.

Robertson P, Campanella R. Interpretation of cone penetrationtests. Part I: Sand. Can
Geotech J 1983;20(4):718–33.

Salehzadeh H, Hozouri A, Golestani A. Correlation between cone and standard penetration
tests. In: 5th Symposium on advances inscience and technology (SASTech 2011), Khavaran
Highereducation Institute, Mashhad, Iran. May 12–14; 2011.

Terzaghi K, Peck R.B.(1948) The Influence of Modern Soil Studies on the Design andConstructions of Foundations.



Uzeilli K.R, Hozouri A, Robertson P. Interpretation of CPT on Geotechnical Parameters.
Sand. Geotech Gate J 2011;20(4):718–33.

154

PART-XIII

THE UTILIZATION OF CPT AND SPT TOOBTAIN SOIL PARAMETERS FOR C- ɸ SOIL
AT UTTARA 3RD PHASE, DHAKA,BANGLADESHBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Zinan A. Urmi
Mehedi Ahmed Ansary

155

1

INTRODUCTION

Soil sampling combined with laboratory testing is the most reliable method to determine soil
properties. Sometimes due to limited budgets, tight schedules, or lack of concern projects do notreceive proper laboratory recommendation. However in many cases subsoil investigation data like
SPT blow count or CPT cone resistance and sleeve friction along with soil type and depth of watertable are available to judge the subsurface soil characteristics. Therefore when laboratory data are notavailable it is a common practice to estimate the soil properties from the SPT-CPT results. Many
empirical correlations have been created between the SPT N-value and CPT cone resistance withother engineering properties of soils. But due to variability of soil properties for same type of soil
from place to place it is very difficult to predict the outcome of those relations without justifying
them for local soil. The local soil may follow previous correlations with slight deviation or may notfollow the trend at all. For the latter case new correlations for local soil must be provided to fulfill
the above mentioned purpose.
The Standard Penetration Test (SPT) is the most common in situ test for site investigations in
Bangladesh and most of foundation designs have been based on SPT-N values and physicalproperties of soils recovered in the SPT sampler. The SPT has some disadvantages such as potential
variability of measured resistances depending on operator variability and possibility of missing
delicate changes of soil properties owing to the inevitable discrete record. Around the world theCone Penetration Test (CPT) is becoming increasingly popular as an in situ test for site investigationand geotechnical design especially in deltaic areas since it provides a continuous record which is freefrom operator variability. For economic consideration it is unlikely that both CPT and SPT are done
for investigation. So it is important to establish correlation between soil parameters individually with
CPT and SPT along with interrelation between these investigation methods.

Fig. 1.1: Standard Penetration Test

Fig. 1.2: Cone Penetration Test

2

BACKGROUND

During the last few decades, many researches have been carried out to obtain soil parameters directlyfrom soil investigation reports for different soils by different researchers around the world. But mostof these researches have been done on clean sand or quartz or pure clay. Unfortunately for
Bangladeshi soil there is hardly researches in this area. Ansary et al (2014) has worked with alluvial
sandy soil in Bangladesh. But no researches regarding silty clay has been done for local soils till now
which indicates the need for justification of existing correlation for local soils and appropriate
correlations that may serve good results.
3

OBJECTIVE OF THE RESEARCH

The present study was aimed to investigate the justification of existing correlation between CPT-SPT
with soil parameters for local silty clay to meet the following objectives.
i.

To determine soil behavior index Ic from CPT

ii.

To interrelate CPT and SPT based on soil behavior index Ic

iii.

To compare the shear strength parameter (Cu) obtained from unconfined compression test
and direct shear test with shear strength parameter (Cu) obtained from SPT blow count(N60) using existing correlations.

iv.

To compare the shear strength parameter (Cu) obtained from unconfined compression test
and direct shear test with shear strength parameter (Cu) obtained from CPT cone resistance(qc) using existing correlations.

v.

To compare the Friction angle (φ) obtained from direct shear test with Friction angle(φ)obtained from SPT blow count (N60) using existing correlations.

vi.

To compare the Friction angle (φ) obtained direct shear test with Friction angle (φ) obtained
from CPT cone resistance (qc) using existing correlations.

vii.

To compare the OCR obtained from consolidation test with OCR obtained from CPT test datausing existing correlations.

viii.

To compare the 50% consolidation time t50 from consolidation test data with t50 obtained from
CPTu dissipation test and to establish correlation among them.

ix.

To establish correlation between Plasticity Index with SPT

x.

To justify existing correlations used for comparison and propose new correlation for local
soil where necessary.

5

FIELD AND LABORATORY INVESTIGATIONSThis chapter presents the details of field and laboratory investigations, equipment used, methodology
and investigation results. For convenience, the chapter is divided into two parts i) Field Investigation
157

and ii) Laboratory investigation. Research location, site geology, sub soil profile and details of SPT
and CPT tests are discussed in the first part. Laboratory test methods and test results are described in
the last part.
FIELD INVESTIGATION
Field investigations were carried out mainly through the application of cone penetration testing(CPT) and standard penetration testing (SPT). A total of six pairs of CPT and SPT were performed indifferent locations within the study area and each pair of CPT and SPT was carried out as close as
possible, maximum horizontal distance was not greater than 1m. In this research, field investigations
were carried out in Uttara Residential Model Town (3rd Phase), Dhaka, Bangladesh as shown in
Figure 3.1.

Figure 5.1: Study location
Geologic formation of research site
The geologic formations of the research site are mainly consisting of alluvial silt and clay. The
alluvial silt and clay part has medium to dark grey silt; color is darker as amount of organic material
increases. A combination of alluvial and paludal deposits has been observed there including floodbasin, back swamp silty clay, and organic rich clay in sag ponds and large depressions. Some
depressions contain peat. Large areas underlain by this unit are dry only a few months of the year;
the deeper part of depressions and bils contain water throughout the year.

158

Cone penetration test
CPT soundings were advanced using a Hogentogler type piezocone penetrometer with a crosssectional area of 10 cm2 and which can measure the pore water pressure (u2), as well as the cone tip
resistance (qc) and sleeve friction(fs). To perform the test, the cone was pushed vertically into theground at a constant rate of approximately 20mm/sec. During the advancement, measurements ofdynamic pore water pressure, tip resistance and sleeve friction were recorded continuously at 10 mm
depth increments. The typical penetration depth for this study was approximately 12-14 m below
from ground surface. CPTu dissipation test were done for each borehole.

Fig 5.2 : Carrying out CPT on site no 16 bore hole 1
Standard penetration test
SPT were conducted per ASTM D1586. Boreholes for the SPT were advanced by wash boring. The
split spoon sampling method was used to obtain soil samples from boreholes and disturbed
representative samples were collected. Samples recovered from boreholes were stored in plastic bags
which were used for laboratory testing. Potential source of uncertainty which may affect SPT Nvalue has been carefully considered. Borehole drilling, soil sampling and SPT N-value recording
procedures were observed by experienced geologist during the entire test program and this individual
provided visual descriptions of the collected samples. The SPT N-value and samples were every .45
m intervals. Rope and cathead SPT hammer-release was used and the efficiency of hammer was
60%.

Fig
5.3(a):Carrying out of SPT by rope hammer(b) Sample collection by split spoon sample

159

Subsoil Profile
The corrected tip resistance (qc1), corrected SPT value N1,60 values are presented in Figure 5.4

Site 2-BH-10
0N-60,N1-60
20Site 13-BH-6

Site 16-BH-6

N-60,N1-60

40

0

20

N-60,N1-60

40

0
0

2

2

2

4

4

4

6

6

6

10

10

10

12

12

12

14

14

14

Depth (m)8Depth (m)0Depth (m)

0

8

16

16

0

1
2
CPT-qt (Mpa)

3

10

20

30

40

8

16
0

1

2

3

CPT-qt (Mpa)

0

2

4

6

CPT-qt (Mpa)

N60

N60

N60

Normalized SPT
blow count N1-60
Normalized cone
resistance qc1 (Mpa)

Normalized SPT blow countN1-60
Normalized Cone
Resistance qc1

Normalized SPT blow
count N1-60
Normalized Cone
Resistance qc1

160

Site 17-BH-11
20

N-60,N1-60

N-60,N1-60

40

0

20

0

40

0

0

2

2

2

4

4

4

6

6

6

8

Depth (m)0Depth (m)Depth (m)0Site 42-BH-9Site 24-BH-7

N-60,N1-60

8

10

10

12

12

12

14

14

14

1

2

3

CPT-qt (Mpa)

30

16

16
0

20

8

10

16

10

0

1

CPT-qt (Mpa)

2

0

0.5

1

1.5

2

CPT-qt (Mpa)

Figure 5.4. Depth versus corrected cone tip resistance (qc1), SPT N60 and N1,60 values for all
boreholes
shown in fig. 3.1
The variation of pore pressure with respect to depth for all the boreholes are shown in figure 5.5161Site 2,BH-10

Site13,BH-6

Site 16,BH-6

Pore Pressure (Kpa)

Pore Pressure (KPa)

Pore Pressure (KPa)

0

500

1000

-200

0

200

400

600

-500

0

0

0

2

2

2

4

4

4

6

6

6

8

8

Depth (m)0Depth (m)Depth (m)

-500

500

1000

8

10

10

10

12

12

12

14

14

14

16

16

16

162

Site 17,BH-11

Site 24,BH-7

Site 42,BH-9

Pore Pressure (Kpa)

Pore Pressure (Kpa)

Pore Pressure (Kpa)

0

50

100

-500

0

500

1000

-500

0

0

0

2

2

2

4

4

4

6

6

6

8

8

Depth (m)0Depth (m)Depth (m)

-50

500

1000

8

10

10

10

12

12

12

14

14

14

16

16

16

Fig 5.5:Variation of pore water pressure (u) with respect to depth (m) for all the boreholes

Friction ratio (Rf or fr ) is defined as the ratio of sleeve friction (fs) to cone tip resistance (qt or qc)
Rf %= 100* fs/qc
163

Variation of friction ratio with respect to depth for all the boreholes are shown in figure 5.6

Site 2 BH-10
Friction ratio Rf
20

40

60

Friction ratio Rf
80

0

20

Friction ratio Rf
40

0

0

0

0

2

2

2

4

4

4

6

6

6

10

10

10

12

12

12

14

14

14

16

16

16

8

Depth (m)8Depth (m)Depth (m)0Site 16 BH 6

Site 13 BH-6

10

20

8

164

Site 17-BH-11

Site 24-BH-7

Friction ratio

Friction ratio Rf

20

40

0

60

20

Friction ratio Rf
0

40

0

0

2

2

2

4

4

4

6

6

6

8

8

Depth(m)0Depth (m)Depth (m)0Site 42 BH-9
50

8

10

10

10

12

12

12

14

14

14

16

16

16

Fig 5.6: Variation of friction ratio (Fr) with depth for all the boreholes.
Based on the results of the subsurface explorations, the subsoil profile at study area can be divided
into three strata. The soil within the test area is primarily comprised of fine sand and silt clay
particles. The top layer consists of light grey to grey medium to loose fine sand trace mica with a
total thickness approximately varied from 4.75 m to 7.5 m. Immediately below this layer, a layer ofdark grey silty clay with organic matter is extended to a depth varied from 7.65 m to 9.45 m. The
bottom layer consists of high plastic grey medium stiff clay or medium plastic soft to medium stiffclay up to the depth of 10.35 m. Ground water table is located at 2.3-2.7 m below from EGL. Note165

that, there was considerable variability in the measured SPT N-value indifferent boreholes atdifferent depths ranging from 2 to 18 and maximum corrected cone tip resistance (qc1) was close to 4
MPa. The pore pressure varies from 0-1000 kpa. The piezometric profile is approximatelyhydrostatic with groundwater at a depth of about 3m. Four out of six boreholes have maximum porewater pressure close to 500kpa, one bore hole has higher pore pressure which has a maximum value
about 1000kpa and other one has lower pore water pressure having a maximum value about
100kpa.Friction ratio is nearly 0 upto 4m depth and has a peak value about 50% in between 7m to
14m depth. Consistency of the soils at different depth varies from stiff to loose.
For the same location subsoil profile is found to be almost similar for different boreholes. For better
understanding ross sectional profile for all the bore holes in X and Y direction keeping borehole 16-6
as origin is given bellow

Fig
5.7: Location sketch of site 16

166

Fig 5.8: Cross sectional Profile in X direction

Fig 5.9: Cross sectional Profile in Y direction
LABORATORY INVESTIGATION
As part of laboratory investigation Atterberg limit test for liquid and plastic limit was done with four
samples as per ASTM Standard D 4318, direct shear test was done with five remolded samples
ASTM standard D-3080, "Standard Method for Direct Shear Test on Soils under Consolidated
Drained Conditions", unconfined compression test was done with four remolded sample according to
ASTM D2166-06 “Standard Test Method for Unconfined Compressive Strength of Cohesive Soil”
and consolidation test was done with six undisturbed clay sample as per ASTM D 2435 – “Standard
Test Method for One-Dimensional Consolidation Properties of Soils.”
Sample Remolding
For remolded samples compaction test was done first per ASTM D 698 “Test Method for Laboratory
Compaction Characteristics of Soil Using Standard Effort”. About 2-2.5kg sample passing #4 sieve167was taken and compacted with different moisture content in a 4-inch-diameter (100 mm) mold whichholds 1/30 cubic foot of soil, and compaction was done by three separate lifts of soil using 25 blows
by a 5.5 lb hammer falling 12 inches, for a compactive effort of 12,400 ft-lbf/ft³. Then moisture
content was plotted against dry density. 95% moisture content at the wet side was taken which was
determined 28.5% was the moisture content for sample remolding and all the samples were remoldedwith this moisture content by compaction as the same manner described above.

Fig 5.10: Compaction test to determine remolding moisture content
Atterberg limits
The Atterberg limits are a basic measure of the critical water contents of a fine-grained soil: its
shrinkage limit, plastic limit, and liquid limit. As a dry, clayey soil takes on increasing amounts ofwater, it undergoes distinct changes in behavior and consistency. Depending on the water content of
the soil, it may appear in four states: solid, semi-solid, plastic and liquid. In each state, theconsistency and behavior of a soil is different and consequently so are its engineering properties.
Thus, the boundary between each state can be defined based on a change in the soil's behavior.

Plastic Limits
The plastic limit (PL) is determined by rolling out a thread of the fine portion of a soil on a flat, nonporous surface. The procedure is defined in ASTM Standard D 4318. If the soil is at a moisture
content where its behavior is plastic, this thread will retain its shape down to a very narrow diameter.
The sample can then be remolded and the test repeated. As the moisture content falls due toevaporation, the thread will begin to break apart at larger diameters. The plastic limit is defined as
the moisture content where the thread breaks apart at a diameter of 3.2 mm (about 1/8 inch). A soil isconsidered non-plastic if a thread cannot be rolled out down to 3.2 mm at any moisture possible.

168

Fig 5.11 : Plastic Limit test
Plastic limits for different boreholes is given in table 5.1
Table 5.1: Plastic limits of different boreholes
Bore Hole No

BH 2-10

BH 13-6

BH 17-11

BH 24-7

Plastic Limit

29.35

21.7

31.94

30.62

Liquid Limits
The Liquid Limit test is being done as per ASTM standard test method D 4318 with Casagrandeapparatus. Soil is placed into the metal cup portion of the device and a groove is made down its
center with a standardized tool of 13.5 millimeters (0.53 in) width. The cup is repeatedly dropped 10
mm onto a hard rubber base at a rate of 120 blows per minute, during which the groove closes
gradually because of the impact. The number of blows for the groove to close is recorded. The
moisture content at which it takes 25 drops of the cup to cause the groove to close over a distance of
13.5 millimeters (0.53 in) is defined as the liquid limit.

Fig 5.12: Liquid limit test with casagrande apparatus
Liquid limits for different boreholes are as follows
Table 5.2: Liquid limits of different boreholes
Bore Hole No

BH 2-10

BH 13-6

BH 17-11

BH 24-7

Liquid Limit

35.8

39.6

46

40.8

Plasticity Index
The plasticity index (PI) is a measure of the plasticity of a soil. The plasticity index is the size of therange of water contents where the soil exhibits plastic properties. The PI is the difference between
the liquid limit and the plastic limit (PI = LL-PL). Soils with a high PI tend to be clay, those with a169

lower PI tend to be silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay. Soil
descriptions based on PI
Table 5.3: Soil classification based on Plasticity Index
Plasticity
Index
Soil Type

0 to 3
Non-plastic

3 to 15

15 to 30>30Slightly

MediumHighlyplastic

plastic

plastic

Plasticity Index for different boreholes was calculated as follows
Table 5.4: Plasticity Index of different boreholes
Bore Hole No
Plasticity
Index

BH 2-10

BH 13-6

BH 17-11

BH 24-7

6.45

17.91

14.06

10.18

The results suggest that three out of four samples were medium plastic and one sample was slightly
plastic.
Soil can be classified based on Atterberg limits as per Unified Soil Classification System (USCS)
Example of 2 Group Symbol: SM
Primary Component (Sand = S) and Secondary Description (M = Silty)
Primary Components: G = Gravel, S = Sand, M = Silt, C = Clay, O = Organic
Secondary Components:
M = Silty: > 12% fines, PI<4 or plots below “A” Line
C = Clayey: > 12% fines, PI>7 and plots on or above “A” line
L = Low Plasticity (Lean for Clay) (LL <50%)
H = High Plasticity (Fat for Clay, Elastic for Silt) (LL ≥ 50%) (e.g. high quality pottery clay)

170

plasticity index vs liquid limit
100

U lineplasticity index

8060

A line

CH

40
MH,OH
20

CL
ML

0
0

10

20

BH 2-10

30

40
50
60
liquid limit (%)

BH 13-670

BH 17-11

80

90

100

BH 24-7

Fig 5.13: Soil classification based on Atterberg limits
Three out of four samples were found to be low plastic silt and one sample was low plastic clay per
USCS
Unconfined Compression Test
Unconfined compression test on four remolded sample was done as per ASTM D 2166 - Standard
Test Method for Unconfined Compressive Strength of Cohesive Soil.

Fig 5.14 : Preparation of samples for unconfined compression test from compacted moldIn the unconfined compression test, each sample was placed in the loading machine between thelower and upper plates. Before starting the loading, the upper plate was adjusted to be in contact withthe sample and the deformation was set as zero. The test then started by applying a constant axial
strain of about 0.5 to 2% per minute. The load and deformation values were recorded as needed for
obtaining a reasonably complete load-deformation curve. The loading was continued until the load
171

values decrease or remain constant with increasing strain, or until reaching 15% axial strain. At thisstate, the sample was at failure. The sample was then removed for measurement of the water content.

Fig 5.15: (a) Recording data for unconfined compression test (b) Failure of sample
As for the results, the axial stress was plotted versus the axial displacement ( Appendix B7-B10).
The maximum axial stress, or the axial stress at 15% axial strain if it occurs earlier, was reported as
the unconfined compressive strength σc. The undrained shear strength was obtained
Su= σc / 2
Undrained shear strength obtained for different bore holes are summarized below
Table 5.5: Undrained shear strength obtained for different bore holes
Sample No
Shearstrength

BH 2-10

BH 17-11

BH 24-7

BH 42-927.58

39.439428.75215

23.1672

Direct Shear Test
Direct shear testing was done per ASTM standard D-3080, "Standard Method for Direct Shear Test
on Soils under Consolidated Drained Conditions" with direct shear apparatus.

Fig 5.16: Direct shear apparatus with shear box
The inside of the shear box was lightly greased to minimize side friction. The lower porous stone
was placed in the shear box. Spacer disks were placed below this stone to adjust the elevation of its
top to accommodate soil samples of different thicknesses. The trimming ring is then carefully
172aligned with the top of the shear box. The trimming ring and top shear box have been machined so
the ring fits into the shallow slot in the top of the shear box, to provide proper alignment. The
sample was then slowly extruded into the shear box by pressing on its top surface, using the top
porous stone or a suitable disk. The upper porous stone and loading cap were placed in the shear
box, and the system to apply the normal-toad was brought into place and a small normal load(seating load) was applied. The normal load was applied through a simple hanger system. The
lateral load was applied using a screw jack which was activated using an electric motor and avariable-speed transmission. The transmission is usually geared to apply about 0.25 inch (typicaldeformation to cause failure) in a time ranging from five minutes to a week. The load transmitted tothe top of the sample was measured using a proving ring.Readings were taken of horizontal
displacement, vertical movement of the top cap, and shearing force, as a function of time. Stressconditions in the sample become increasingly uncertain as deformation continues so the test isusually stopped when shearing stress reached a peak value.The procedure was repeated thrice foreach sample with three different normal stresses of 25kN/m2,50kN/m2 and 100kN/m2. Peak shear
stress for each normal stress was obtained by plotting shear stress against displacement. Peak shear
stresses were then plotted against normal stress. The slope angle of this curve represents the friction
angle (φ) and the vertical intercept represents the shear strength (Su).
The internal friction angle and shear strength for different bore holes are summarized below in thetable
Table 5.6: The internal friction angle and shear strength for different bore holes
Sample No

BH 2-10

BH 13-6

BH 17-11

BH 24-7

BH 42-9

Shear strength (Su)

14.8

20.1

25

41

22

11

30

32

20

19

Internal friction
angle (φ)

Consolidation Test
Consolidation test was done with six undisturbed clay sample as per ASTM D 2435 – “Standard Test
Method for One-Dimensional Consolidation Properties of Soils.” It was the most time-consuming
laboratory investigation.

173

Fig 5.17: Consolidation test Apparatus
The change in height of soil sample for loading and unloading stage were recorded with respect totime. At first load was increased incrementally from 0 to 5,25,100,200,400 and 800 kPa , thendecremented from 800 to 400,100 and 10kPa. Load increments were done at one day interval. Timevs vertical dial reading was plotted to obtain 50% consolidation time t50 and 90% consolidation timet90 (Appendix B1-B6)
For each sample e-logP (void ratio vs pressure) curve and Cv (co-efficient of volume
compressibility) against Pressure curve was obtained. Pre-consolidation pressure was obtained using
e-logP curve (Appendix B1-B6)
Calculation of each borehole to form e-logP curve and Cv against Pressure curve are discussed
separately below.
BH 13-12 depth 6.3m
Table 5.7: Calculation for co efficient of volume compressibility (Cv) and compression index (Cc)for BH 13-12
P

Loading

FDR

∆H

Ht

Hv

(kpa)

(in)

(in)

(in)

(in)

0

0.089

1

0.528

e

0.096

0.99

0.129

0.521

0.151

(in)

t50

t90

cv

Cc

from
t50

t90

1.105

0.1
0.98

0.96

0.488

1.035

0.022
50

min

1

0.033
25

time

1.119

0.007
5

Ht(av)

1.7

4

0.02760.0506

0.155

4.5

1.44

0.00990.1327

0.296

0.95
0.94

0.466

0.988

174

0.042
100

0.193

0.92
0.9

0.424

0.899

0.07
200

0.263

0.83

0.368

0.354

0.751

0.72

0.47

0.00540.0112

0.493

12.5

17.2

0.00290.0091

0.742

17

14

0.00170.0091

0.714

16

24.1

0.0014

0.004

0.77
0.249

0.528

0.102
800

16

0.86

0.105
400

7.7

0.67
0.62

0.148

0.313

0.64

0.169

0.359

0.72

0.245

0.52

-0.02
400

0.448
-0.08

100

Unloading

0.372
-0.14

10

0.23

0
0.86

0.286

0.607

1.2

0.8

cv*10^3

void ratio,e

1

0.6
0.4
0.2
Loading

0
1

140
120
100
80
60
40
20
0
0

Unloading10
100pressure,P1000

Fig 5.18: e-logP curve for BH 13-12

500
1000
pressure (kpa)t50
t90

Fig 5.19: Cv Vs Pressure curve for BH 13-12
BH 16-3 depth 6.3m
Table 5.8: Calculation for co efficient of volume compressibility (Cv) and compression index (Cc)for BH 16-3

Loading

P

FDR

∆H

Ht

Hv

(kpa)

(in)

(in)

(in)

(in)

0

0.08941

0.4499e

0.096

0.99340.1102

cv from

(in)

t50

t90

t50

Cc
t90

0.44330.805850.03690.98630.97920.0128min

0.99670.014225

time

0.81785

0.00665

Ht(av)

0.42910.780043.8

10.01260.206

0.07730.9728

175

50

0.123

0.9664

0.41630.75677

0.0212100

0.14420.94520.20240.39510.718230.887

0.25290.33690.612430.83650.3299

0.041

0.128

7.5

10.24

0.006

0.019

0.35158

40.0052

0.044

0.305

14

4

0.0026

0.039

0.465

16

33.64

0.002

0.004

0.86175
0.28640.520630.077
800

0.00720.91610.0505400

4.84

0.95580.0582
200

6.5

0.798
0.75950.20940.38066

0.76390.21380.38866

0.78470.2346

0.426470.83720.2871

0.521910.0044400

0.32550.0208

Unloading1000.30470.0525100.2522

P= Pressure, FDR=Final Dial Reading, ∆H= Change in specimen height, Ht= Final Specimen height,
Hv=Height of void
e=Void ratio
0.9
0.8
0.7

void ratio,e

0.6
0.5
0.4
0.3
0.2
0.1
0
1

10

pressure,PLoading

100

1000

UnloadingFig 5.20: e-logP curve for BH 16-3
176

cv against pressure curve for Bh-16-3,UD-1,Depth 6.3
250

cv*10^3

200
150
t50

100

t90
50
0
0

100

200

300

400
500
pressure (kpa)

600

700

800

900

Fig 5.21: Cv Vs Pressure curve for BH 16
BH 17-16 depth 8.1m
Table 5.9: Calculation for co efficient of volume compressibility (Cv) and compression index (Cc)for BH 17-16

P

FDR

∆H

Ht

Hv

(kpa
)

(in)

(in)

(in)

(in)

0

0.0852

1

0.4499e0.442325

0.42170.1372

0.176

t90

t50

t90

0.0
5

6.2

18.
1

0.007
7

0.0
1

0.1
4

6.5

9.6
1

0.007

0.0
2

0.2
3

12

20.
3

0.003
5

0.0
1

0.3
5

0.959
9
0.948

0.3979

0.723
3
0.928
6

0.0388
100

t50

0.766
6

0.0238
50

(in)

Cc

0.982
1
0.971
8

0.1134

cv
from

0.804

0.0206

Loading

min

0.996
2
0.992
4

0.0928

time

0.817
9

0.00765

Ht(av)

0.909
2

0.3591

0.652
8

177

0.87990.0586
200

0.850
6

0.23460.3005

0.546
3

0.779
6

0.30560.22950.417
20.3836

0.002
7

0.0
2

0.4
3

14

13.
9

0.002
3

0.0
1

0.4
7

13

11.
6

0.002
1

0.0
1

0.740
6

0.078
800

10.
2

0.815
1

0.071
400

14

0.701
6

0.1515

0.275
4

0.706
4

0.1563

0.284
1

0.727

0.1769

0.321
6

0.776
6

0.2265

0.411
7

10

pressure,P

0.0048400

0.37880.0206

Unloading100

0.35820.0496100.30860.9
0.8
0.7
void ratio,e

0.6
0.5
0.4
0.3
0.2
0.1
0
1

Loading

100

1000

UnloadingFig 5.22: e-logP curve for BH 17-16

178

25

cv*10^3

20

15

10

t50
t90

5

0
0

200

400
600
pressure (kpa)

800

1000

Fig 5.23: Cv Vs Pressure curve for BH 17-11
BH 24-2 depth 8.55
Table 5.10: Calculation for co efficient of volume compressibility (Cv) and compression index (Cc)for BH 24-2
P

FDR

∆H

Ht

Hv

(kpa)

(in)

(in)

(in)

(in)

0

0.058

1

0.384

e

0.069
0.09

50

0.107

0.99

0.373

0.134

0.97

0.352

0.57

0.95

0.335

0.54

0.189

400

0.262

0.92

0.309

t50

t90

0.05

0.5

0.9

1.44

0.0524

0.14

0.09

0.75

1.96

0.0605

0.1

0.14

1.4

2

0.031

0.09

0.3

2.6

3.063

0.0152

0.06

0.4

5.1

14

0.0067

0.01

0.54

5.5

32

0.005

0

0.897
0.87

0.253

0.41

0.8

0.18

0.29

0.833

0.1
0.362

t90

0.938

0.07

800

t50

0.96

0.06
200

(in)

Cc

0.979

0.03
100

cv from

0.61

0.02

Loading

min

0.995

0.02
25

time

0.62

0.01
5

Ht(av)

0.746
0.7

0.08

0.13

0.7

0.088

0.14

-0.01

Unloading

400

0.354
-0.02

179

100

0.33

10

0.289

0.73

0.113

0.18

0.77

0.154

0.25

0.7

160

0.6

140
120

0.5

cv*10^3

void ratio,e

-0.04

0.4
0.3

100
80

t50

60

0.2

t90

40

0.1

20

0

10 pressure,P 100
Loading
Unloading

1

0

1000

5.24: e-logP curve for BH 24-2

0

500

1000

pressure (kpa)Fig

Fig 5.25: Cv Vs Pressure curve for BH 24-2

BH 2-1 depth 7.65m
Table 5.11: Calculation for co efficient of volume compressibility (Cv) and compression index (Cc)for BH 2-1
P

FDR

∆H

Ht

Hv

e

(kpa)
0

(in)
0.0652

(in)

(in)
1

(in)
0.367

0.667151

50.07380.99140.35840.651518

0.00860.088

50

0.97720.10230.34420.32980.30640.27410.498273

0.87140.23592.25

0.0281

0.0913

0.087

3.1

6.25

0.01490.03190.14133.25

2.89

0.0137

0.06640.19512.9

4.84

0.01450.03730.21564.2

5.76

0.00930.02910.25423.2

6.76

0.0111

0.02270.889250.23840.433376

0.0421800

1.70.923250.90710.1938t90

0.03690.55699

0.0357400

Cc

0.951150.93940.1581t90

0.599527

0.0323
200

t50

cv
from
t50

0.97005
0.96290.1258(in)

0.625704

0.0235100

min

0.98430.0143

Loadingtime

0.99570.014225

Ht(av)

0.85035
0.82930.19630.356844

0.83390.20090.3652060.85040.21740.395201

0.89310.26010.472823

0.0046400

0.23130.0165

Unloading100

0.21480.0427100.1721180

80

cv*10^3

void ratio,e

100

0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3

60

t50

40

t90

20
1

10

pressure,PLoading

100

1000

0
0

Unloading

5.26: e-logP curve for BH 2-1

500

1000

pressure (kpa)Fig

Fig 5.27: Cv Vs Pressure curve for BH 2-1

BH 17-5 depth 5.85m
Table 5.12: Calculation for co efficient of volume compressibility (Cv) and compression index (Cc)for BH 17-5
P

FDR

∆H

Ht

Hv

(kpa)

(in)

(in)

(in)

(in)

0

0.0557

1

0.531

e

0.0574

0.99830.087

0.529350

0.49970.48990.47420.44830.956

0.87450.24133.24

0.04760.063

0.06948

2.89

0.00570.068

0.11125.1

4.84

0.00870.04

0.18346.5

14.82

0.00660.012

0.30324.1

15.21

0.00960.011

0.42573

12.25

0.01170.012

0.89590.40550.865

0.0601800

10.930250.91730.18120.09031.011

0.0428400

t90

0.95105
0.94320.1384t50

1.045

0.0259200

t90

0.96380.95890.1125t50

1.065

0.0157
100

(in)

Cc

0.98350.9687

0.0968

cv
from

1.129

0.0098
Loadingmin0.999150.0296
25

time

1.132

0.00175

Ht(av)

0.844450.81440.34540.736

0.8186

0.34960.745

0.85770.38870.829

0.0042400

0.23710.0153

Unloading
10

0.198

181

1.2
1

cv*10^3

void ratio,e

1.1
0.9
0.8
0.7
0.6
1

10pressure,P 100
Loading
Unloading

1000

80
70
60
50
40
30
20
10
0

t50
t90

0

Fig 5.28: e-logP curve for BH 17-5

500

pressure (kpa)1000

Fig 5.29: Cv Vs Pressure curve for BH 17-5

Calculation of Over Consolidation Ratio (OCR)
Table 5.13: Calculation of OCR for different boreholes
depth

OCR=

Borehole noσp' (kpa)(m)

σv(kpa)σv'(kpa)

σp'/ σv'

13-12

93

6.3

83.19

38.9972.133241

16-3

130

6.3

120.1938.9973.082032

17-16

88

8.1

78.19

50.1391.559465

17-5

121

5.85

111.1936.2115

3.070572

2--1

91

7.65

81.19

47.3535

1.714551

24-2

140

8.55

130.1952.92452.459919

Here,
σp'=Pre-consolidation pressure, σv= Overburden stress and σv'=Effective overburden stress

6

RESULTS COMPARISON AND DISCUSSIONS

Correlation of CPT and SPT based on soil behavior index
Soil Behavior index Ic was determined for all the boreholes using the equation 2.1 provided byRobertson (1990)
ISBT = [(3.47 - log(qc/pa))2 + (log Rf + 1.22)2]0.5 --------- (2.1)

182Site 2 BH-10
2.5

Ic SBT

SBT index Ic
3.5

4.5

1.5

2.5

3.5

1.5

4.5

0

2

2

2

4

4

4

6

6

6

Depth (m)008Depth (m)

10

10

10

12

12

12

14

14

14

16

16

16

8

Site 17-BH-11

Site 24-BH-7

3.5

4.5

2.5

Ic SBT
1.5

3.5

0

0

0

2

2

2

4

4

4

6

6

6

8

Depth

Depth (m)

2.5

1.5

8

5.5

Site 42 BH-9

Ic SBT

Ic SBT
1.5

3.5

8

Depth

Depth (m)1.5

Site 16-BH-6

Site 13 BH-6

Ic SBT

2.5

3.5

4.5

8

10

10

10

12

12

12

14

14

14

16

16

16

Fig 6.1: SBT profile for all the bore holes
All the bore hole has similar type of variation in behavior index(Ic ) and it reached a peak value about
3.5 to 4 in all the bore holes at a depth greater than 5m.
Calculated CPT based Ic was plotted against the ratio of CPT cone resistance qt to SPT blow countN60 (qt/N ) and compared to the existing correlation between qt/N and Ic provided by Jefferies &Davies (1993) which was modified by Robertson and wride in (1998) and Robertson(2012) as per
equation 4.2 and 4.3 discussed in section 4.
183

(qt/pa)/N60 Vs CPT-based SBT index Ic.

100(qt/pa)/N60

10

1

0.1
1.5

2
2.5
Modified Jefferies & Davies (1993)

3
3.5
Robertson(2012)
Ic

4
Study data

4.5

Fig 6.2 : (qt/pa)/N60 Vs CPT-based SBT index Ic comparison with existing correlations
Fig 6.2 shows that qt/N ratio for local soil shows the same pattern as existing correlations. qt/N ratio
for selected data points varies from 0.6 to 10 with a variation of SBT index from 1.9 to 3.9 whereas
existing correlations suggest that with similar variation of SBT index qt/N has a range of 1 to 5.
From the graph, we can see the number of data points showing deviation is very less and about 85%of the data points falls within the range of existing correlations. So, we can conclude that CPT data
are reliable to calculate SBT index and also, SBT index based CPT-SPT correlations are fairly
applicable for local soil.
Correlation of SPT with undrained shear strength Su or Cu
Shear strength obtained from direct shear test and unconfined compression test were compared withshear strength obtained from SPT based correlation provided by Kulhawy and Mayne (1990) as per
equation 4.7 mentioned in section 4.
Table 6.1: Comparison of shear strength from laboratory test results with SPT based shear strength
Sample No

Observed UC Direct shear(kpa)

BH 2-10SPT N60

Cu (Kulhawy Mayne

(kpa)
27.58

BH 13-6

1990) (kpa)14.8

530.3975

20.1

4.375

26.5978125

BH 17-1139.439425

530.3975

BH 24-7

28.75215

41

4.57

27.783315

BH 42-923.1672

22

3.87

23.527665

Three out of four unconfined compression test results coincide with SPT derived shear strength but
direct shear test results show deviation. This is mainly because Kulhawy and Mayne established the184empirical correlation between SPT and undrained shear strength for pure clay sample based on
unconfined compression test results. Besides direct shear test is suitable for fine grained soil not pureclay. A slight variation in moisture content can significantly affect direct shear test. Only a single
compaction test was done to determine optimum moisture content for all the sample remolding.
Thus, some samples may have moisture content more than necessary which may cause thedeviations.
Both of the laboratory test results were plotted against SPT on the same graph with relationshipprovided by Kulhawy-Mayne (1990)

Cu Vs SPT curve50

BH 17-11

40
Cu

30
20

Cu = 9.1912N60 - 12.637
R² = 0.5044

10
0
3.7

3.9

4.1

4.3
4.5
SPT N60
Cu (Kulhawy Mayne 1990)
Observed UC

4.7

4.9

5.1

Mean line for UC

Fig 6.3: Cu Vs SPT blow count N60 curve for comparison of unconfined compression test results
From fig 6.3 we see that only Shear strength obtained from the sample of BH 17-11 shows deviation,
yet the mean line of unconfined compressive results was very close to that of Kulhawy and Mayneand has a R2>0.3 which ensures good applicability of this correlation for local soil.

Cu Vs SPT curve50

y = -1.4987x + 31.419
R² = 0.0051

Cu (kN/m2)

40
30
20
10
0
3.7

3.9

4.1

4.3

Cu (Kulhawy Mayne 1990)

4.5
SPT N60

4.7

4.9

5.1

Direct Shear Test

Fig 6.4: Cu Vs SPT blow count N60 curve for comparison direct shear test results
Fig 6.4 shows the poor applicability of existing correlation and the study data points do not maintainany different correlation with SPT as the mean line has a R2<<0.3.
185Correlation of CPT with undrained shear strength Su or Cu
Shear strength obtained from direct shear test and unconfined compression test were compared withshear strength obtained from CPT based correlation as per equation 2.14 with modified Nkt value
providedbyRobertson(2012)

inequation

2.15

mentionedinchapter2.

Table 6.2: Comparison of shear strength from laboratory test results with CPT based shear strength
SampleNkt = 10.5 +No

Observed

DirectFr7

qclog(Fr)(kpa) (Robertson 2012 ) (kpa)

14.8 13.71

18.45926218

310

13.00431174

20.1

6.41

16.14800621

313

15.05139377

39.4394

25 15.65

18.86160039

730

34.99437939

28.75215

41

5.85

15.87009106

650

36.54988479

23.1672

22

11.7

17.97730103

597

29.31752653

UC(kN/m2) shear(kN/m2)

Cu = (qc− σvo)/Νkt

BH 21027.58

BH 136
BH 1711
BH 247
BH 429

We observe from table 6.2 that with a variation of qc from 310kpa to 730kpa the existing correlation
gives a Cu range of 13 to 29 where laboratory test results give a Cu range of 23.17 to 39 for
Unconfined compression test and 14.8 to 41 for direct shear test.
Both laboratory test results were plotted against SPT on the same graph with relationship provided

Cohesion coeffcient Cu

by Robertson (2012) to justify the applicability this correlation to local soils.
Cohesion coeffcient Cu Vs Normalized Cone resistance qc

60

Cu= 2qc/σvo + 11.31
R² = 0.4

40
20
0
0

100

200

Unconfined Compression test

300
400
500
600
Normalized Cone resistance qc
Direct shear
Robertson 2012

700

800

900

Cu= 2qc/σvo + 11.31

Fig

4.5: Cu Vs CPT cone resistance qc curve for comparison laboratory test results

186

The study data points follows a similar linear pattern as correlation stablished by Robertson (2012)
but better suits with Cu= 2qc/σvo + 11.31 rather than Cu = (qc− σvo)/Νkt . The proposed correlation
has R2>0.3 and has a scope of development when large amount of data points are available.
Correlation of SPT with internal friction angle φFriction angle obtained from direct shear test was compared with SPT based friction angle withequation 2.4, 2.5 and 2.6 provided by Wolff (1989), Kulhawy and Mayne (1990) and Hatanaka and
Uchida (1996) respectively.
Table 6.3: Comparison of friction angle from direct shear test results with SPT based friction angle
From direct

kulhawy andHatanaka andwolff

shear test (inmayne 1990,(ɸ)

uchida 1996

1989

(degree)(degree)(degree)

SampleSPT

No

N60(avg) degree)

BH 13-6

4.38

30

24.89

28.49956106

28.40

5

32

25.88

29.08641298

28.59

BH 24-7

4.57

20

25.17

28.68691495

28.46

BH 42-9

3.87

19

23.75

27.99397806

28.25

BH 1711

We can see from Table 6.3 that for a variation of SPT from 3.87 to 5 angle of internal friction
remains within the range of 24-29 in the existing correlations whereas results obtained from direct
shear test shows a variation of ɸ has a range of 19 to 30 which is close to the existingcorrelations.For better understanding friction angle from direct shear test has been plotted against
SPT blow count N60 in the same graph where existing correlations have been illustrated.

Friction angle (ɸ) vs SPT blow count N60 curve

60

ɸ

40
20
0
3

3.5
wolff 1989

4

N60

4.5

5

5.5

6

kulhawy and mayne 1990,(ɸ)

Fig 6.6 : Friction angle (ɸ) vs SPT blow count N60 curve
From figure 6.6 we see the plotted study data points has a steeper curve than existing correlations. So
the study points were plotted separately to obtain a new correlation for local soil.

187

Obtained ɸ vs N60 curve50

ɸ= 2.1123*N601.6627
R² = 0.3612

Obtained ɸ

40
30
20
10
0
2

2.5

3

3.5

4

4.5

N60

5

5.5

6

6.5

Fig 6.7: Friction angle (ɸ) vs SPT blow count N60 curve for selected data points
The above figure suggests a new correlation of ɸ= 2.1123*N601.6627 for local soil. This correlation
gives a scope for obtaining internal friction angle directly from SPT data but more data points are
required to establish a reliable correlation for local soil.
Correlation of CPT with internal friction angle φFriction angle obtained from direct shear test was compared with CPT based friction angle withequation 2.9, 2.10(a) and 2.10(b) provided by Robertson and Campenella (1983), Kulhawy andMayne (1990) and Minmura (2003) respectively as discussed in chapter 2.
Table 6.4: Comparison of friction angle from direct shear test results with CPT based friction angle
Fromdirectcpt

Sampleshear test

qc(MPa) Campanella

No

(φ)

BH 13-6

Robertson &(1983) (degree)

Kulhawy &MimuraMayne(2003)(1990) (degree)

(deg)

30

0.313

13.04

16.730

22.23

11

32

0.73

20.3

20.78

26.28

BH 24-7

20

0.65

19.29

20.22

25.72

BH 42-9

19

0.597

18.67

19.82

25.32

BH 2‐10110.31 13

16.68

22.18

BH 17-

From above table we observe that for a variation of cone resistance from .31Mpa to .73 Mpa existingcorrelations provides a range of 13-26 o whereas friction angle from direct shear test varies from 11
to 32o.

188

Data points BH 13-6 and BH 17-11 shows larger deviation it may be because of the selection of
optimum moisture content for remolding as explained before.For better understanding friction angle
from direct shear test has been plotted against CPT cone resistance qc in the same graph where
existing correlations have been illustrated.

Friction angle (ɸ) vs cone resitance (qc) curve35

BH 17-11
BH 13-630

Friction angle (ɸ)

25
20
15
10
5
0
0

0.1

0.2

0.3

0.4
0.5
cone resitance (qc)

From direct shear test
Robertson Campanella (1983)

0.6

0.7

0.8

0.9

Average from direct shear test
Kulhawy and Mayne 1990

Fig 6.8: friction angle Vs CPT cone resistance qc
Above graph shows that three out of four data points falls on the Robertson Campenella (1983)
curve. Two samples show greater deviation yet the mean curve obtained from direct shear test falls
within the range of the existing correlations and follows a similar pattern.
To establish correlation between CPT cone resistance and internal friction angle for local soil, data
points of BH 13-6 and BH 17-11 (larger deviation) was neglected.

189

Obtained Friction anle (ɸ) vs cone resitance (qc) curve

Friction anle (ɸ)

25ɸ = 12.175ln(qc) + 25.262
R² = 1

20
15
10
5
0
0

0.1

0.2

0.3

0.4
0.5
cone resitance (qc)

0.6

0.7

0.8

Fig 6.9 : New correlation between friction angle(φ) and cone resistance(qc) for local soilFig 6.9 shows a strong correlation between friction angle and CPT having a R2=1. So the proposed
new correlation for local soil is ɸ = 12.175ln(qc) + 25.262
Comparison of t50 from consolidation test and CPTu dissipation test
CPTu dissipation test was done on different depths on different bore holes (details appendix C Test
No F7). These depths range from 6-8m having a overburden pressure about 100kpa. So t50 obtained
from dissipation tests were compared to t50 obtained for 100kpa loading during consolidation test.
The bore hole number of consolidation samples were different from the bore hole numbers of CPTu
dissipation tests. But as discussed in chapter 3 and illustrated in fig 3.7 and 3.8 that the crosssectional profile of boreholes of the same site is uniform so the effect of borehole numbers being
different is neglected.
Table 4.5: Comparison of t50 from consolidation test and t50 CPTu dissipation test
Site Not50 obtained from consolidation
test(min)
t50 0btained from cptu dissipation test(min)

Site 13Site 24Site 16Site 17

7.7

1.4

7.5

12

2.8

4

4

8

The table shows lower t50 values for CPTu dissipation test than consolidation test other than site 24.
To determine whether t50 values obtained from laboratory and field data maintains any correlation,
t50 obtained from field data was plotted against t50 obtained from consolidation test and a correlation
has been proposed between these two as follows
t'50 = 1.0346*t50 - 4.4466
where t’50= 50% consolidation time from CPTu dissipation
190

field data (t'50) vs laboratory data (t50)

t50 0btained from cptu dissipation test (min) t'50

12
t'50 = 1.0346*t50 - 4.4466
R² = 0.9331
10

8

6

4

2

0
4

6

8
10
12
t50 obtained from consolidation test(min)14

16

Fig 4.10: 50% consolidation time from field data (t'50) vs laboratory data (t50)
Correlation of Over Consolidation Ratio (OCR) with CPT cone resistance
OCR obtained from consolidation tests were compared to OCR obtained from the empiricalcorrelations with CPT cone resistance using equation 2.19, 2.25 and 2.26 provided by Kulhawy andMayne (1990), Karlshud et al (2005) and Been et al. (2010) as discussed in chapter 2.
Table 4.6 : Comparison of laboratory obtained OCR with CPT based OCR
B
H
N
o.

13
12
16
-3

Kulhawy & Mayne(1990)

From Consolidation test
σp'
(kp
a)

dept
h
(m)

σv
(kpa
)

σv'
(kpa)

OC
R

K

93

6.3

83.1
9

38.9
97

2.1
3

0.3
3

130

6.3

120.
2

38.9
97

3.0
8

0.3
3

Karlshrud et al(2005)

Been et al. (2010)

q(t)
kpa

OC
R

OCR=.25*Qt1
^1.2

fr
kp
a

N(K
t)

s
u

Q(t
1)

OC
R

100.8

142.
4

0.5

1.182808829

12.
7

18.2
2

8

3.7

0.8

100.8

654.
4

4.5
2

7.374193329

1.8
5

12.3
7

5
3

17

8.3

σv(kp
a)

191

17
16
17
-5

88

8.1

78.1
9

50.1
39

1.5
6

0.3
3

129.6

300.
8

1.4
7

2.146162517

0.4
4

8.00
4

3
8

6

3.9

121

5.85

111.
2

36.2
12

3.0
7

0.3
3

93.6

132.
8

0.2

1.188945317

2.5
4

13.3
3

1
0

3.7

1.1

2-1

91

7.65

81.1
9

47.3
54

1.7
1

0.3
3

122.4

304

1.5
5

2.327907974

5.4
7

15.6
7

1
9

6.4

1.9

24
-2

140

8.55

130.
2

52.9
25

2.4
6

0.3
3

136.8

752

3.8
8

6.039671264

5.0
2

15.4
1

4
9

14

5.1

From above table we see that for a variation of qc value from 132.8 kpa to 752kpa CPT based OCR
varies from 1 to 4.5 (Kulhawy and Mayne 1990), 1-7.37 (Karlshrud et al 2005), 1-8.3 (Been et al2010) whereas laboratory test results provide OCR range 1.56 to 3.08. Empirical OCR <1 was
ignored as OCR cannot be less than 1.
Obtained OCR from consolidation tests show least deviation with OCR obtained as per Kulhawy andMayne (1990) but other correlations show significant deviation with laboratory results.All the OCR
values were plotted against CPT cone resistance for better understanding.

OCR vs Cone resistance
9
8
7

OCR

6
5
4

y = 0.0007x + 2.0856
R² = 0.0695

3
2
1
0
0

100

200

300
400
500
Cone resistance,qc

From Consolidation result
Been et al. (2010)
Linear (From Consolidation result)

600

700

800

kulhawy & mayne (1990)
Karlshrud et al (2005)

Fig 6.11: Over consolidation ratio vs CPT cone resistance curve for Laboratory test results and CPT
based correlations

192

From Fig 6.11 we see the mean line for OCR obtained from consolidation test has a very low R2value which implies CPT value doesn’t affect the over consolidation ratio for local soil.
Correlation of Atterberg Limits with Normalized SPT blow count
There is no available correlation that directly relates Atterberg limits with SPT blow count. An
approach to such correlation was made by Mostafa Abdou Abdel Naiem Mahmoud (2013) but the
study failed to stablish any correlation between LL, PL or PI with normalized SPT. Such approachhas been taken here with the hope of a better result for local soil.
Firstly Liquid limit and Plastic Limit were plotted against normalized SPT blow count (N1,60). N1,60 iscorrected N value for overburden pressure using the formula of Boulanger (2003) which is a
modification of Liao and Whitman (1986)
N1,60=CN* N60
Where CN=(pa/σ’v) m ≤1.7 and m=.784-.0768*N600.5
Corrected SPT number (N1-60)
versus liquid limit (LL)35

liquid limit (LL) %Plastic limit (PL) %Corrected SPT blow count (N1-60)
versus Plastic limit (PL)302520PL = 8.919N1,60 - 7.0952
R² = 0.4349

15
10
3.4

3.9
4.4
Corrected SPT number (N1-60)

4.9

50

y = -5.1012x + 60.853
R² = 0.1691

45
40
35
30
3

3.5
4
4.5
Corrected SPT number (N1-60)

5

Fig 6.12: Corrected SPT blow count (N1-60) versus Plastic limit (PL) and Liquid limit (LL)
Above figure shows Plastic limit shows a correlation to normalized SPT blow count with R2 =.43
whereas plots regarding Liquid limit was found to be scattered indicating no noticeable effect on
SPT blow count.
To correlate plasticity index with SPT value a similar approach like Stroud (1974) was taken and theratio of shear strength to SPT blow count (f1) was plotted against PI and compared to the pattern ofStroud (1974)
Table 6.7: Calculation of f1
site
BH 2-10
BH 13-6
BH 17-11
BH 24-7

SPT blowcount, N60
4.4
3.57
3.95
4

Cu from DS

f=Cu/N60

14.8
20.1
25
41

3.363636364
5.630252101
6.329113924
10.25
193

f1 plotted against plasticity index
12
f1=Cu/N60(kN/m2)

10
8
6
4
2
0
8

13
18
plasticity index PI (%)

23

Fig 6.13: Variation of f1 with PI for study dataFig 6.14: Variation of f1 with PI as per

Stroud (1974)
In above figures for both of the curves Plasticity index decreases with increasing f1 maintaining
similar pattern, so it can be concluded that plasticity index can be correlated with SPT blow counts.
To correlate Plasticity index with SPT blow counts Plasticity Index was plotted against N60

Plasticity Index(PI)Plasticity Index(PI) vs SPT blow count N-60
20
18
16
14
12
10
8
6
4
2
0

PI=-14.02*N60 + 67.948
R² = 0.9301

3.4

3.6

3.8

4
4.2
SPT blow count N-60

4.4

4.6

Fig 6.14: Correlation of Plasticity index (PI) with SPT blow count N60
Above figure illustrates a linear relationship between PI and N60 and Plasticity index decreases withincreasing SPT blow count. The correlation can be given as
PI=-14.02*N60 + 67.948

7CONCLUSIONS

The following conclusion can be drawn from present study

194a) CPT data are reliable to calculate SBT index from the equation provided byRobertson (2012)
ISBT = [(3.47 - log(qc/pa))2 + (log Rf + 1.22)2]0.5b) SBT index based CPT-SPT correlations provided by Robertson and Wride (1998)
and Robertson (2012) are fairly applicable for local soil.
c) SPT based correlation to obtain undrained shear strength (Su) by Kulhawy and Mayne(1990) ensures good applicability of this correlation for local soil.
d) Correlation between shear strength (Su) and CPT cone tip resistance shows similar
pattern but not exactly the same as Robertson (2012). So a new correlation was
proposed as follows
Cu= 2qc/σvo + 11.31-------------(5.1)e) A new correlation for SPT blow count and internal friction angle(ɸ) for local soil was
given by
ɸ= 2.1123*N601.6627 ----------------(5.2)
f) Study soil follows the correlation between friction angle and CPT cone resistanceprovided by Robertson and Campanula (1983) with slight deviation. A better
correlation was proposed for local soils asɸ = 12.175ln(qc) + 25.262 ----------(5.3)g) A new correlation between 50% consolidation time obtained from consolidation test(t50) and
CPTu dissipation test (t’50) has been proposed as follows
t'50 = 1.0346*t50 - 4.4466-----------(5.4)h) CPT value doesn’t affect the over consolidation ratio for local soil.
i) A correlation between Plastic Limit and SPT blow count is proposed as given bellow
PL = 8.919N1,60 - 7.0952--------------(5.5)
195j) Plasticity index decreases with increasing SPT blow count. The correlation can begiven as
PI=-14.02*N60 + 67.948-----------------(5.6)
References
Alam et al, J.W. 1990. Geological Map of Bangladesh. Dhaka: Geological Survey of Bangladesh.
Ameratunga et al, C.2016. Correlations of Soil and Rock Properties in Geotechnical Engineering.
P.144
Alan Reid and Dr John Taylor, geotechnical engineers, South Lanark shire Council, The misuse of
SPTs in fine soils and the implications of Eurocode 7.
Douglas, B.J., and Olsen, R.S., 1981. Soil classification using electric cone penetrometer. In
Proceedings of Symposium on Cone Penetration Testing and Experience, Geotechnical Engineering
Division, ASCE. St. Louis, Missouri, October 1981, pp. 209-227.
Hiroshan Hettiarachchi,Timothy Brown, “Use of SPT Blow Counts to Estimate Shear Strength
Properties of Soils: Energy Balance Approach” Article in Journal of Geotechnical andGeoenvironmental Engineering · June 2009
H.M. Mominul, M.A. Ansary & M.J. Abedin. Bangladesh University of Engineering andTechnology, Dhaka, Bangladesh, “Applicability of existing CPT, SPT and soil parametercorrelations for Bangladesh” in 3rd International Symposium on Cone Penetration Testing, Las
Vegas, Nevada, USA – 2014
Jefferies, M.G., and Davies, M.P., 1993. Use of CPTU to estimate equivalent SPT N60. Geotechnical
Testing Journal, ASTM, 16(4): 458-468.
Kasim, A.Chu, M. & Jensen, C. 1986. Field Correlation of Cone and Standard Penetration Tests. J.
Geotech. Engrg., 112(3):368–372.
Kulhawy, F.H. & Mayne, P.W. 1990. Manual on estimating soil properties for foundation design.
NewYork: Electric PowerResearch Inst., Geotechnical Engineering Group, (EPRI-EL-6800): 2-36 to
2-28.
Long, M., 2008.

Design parameters from in situ tests in soft ground – recent developments.

Proceedings of Geotechnical and Geophysical Site Characterization. Taylor & Francis Group, 89116
Lunne, T., Robertson, P.K., and Powell, J.J.M., 1997. Cone penetration testing in geotechnicalpractice. Blackie Academic, EF Spon/Taylor & Francis Publ., New York, 1997, 312 pp.
196

Molle, J., 2005. The accuracy of the interpretation of CPT-based soil classification methods in soft
soils. MSc Thesis, Section for Engineering Geology, Department of Applied Earth Sciences, Delft
University of Technology, Report No. 242, Report AES/IG/05-25, December.
McNulty, G. & Harney, M. D. 2010. Comparison of CPT-and DMT-correlated effective friction
angle in clayey and siltysands. 2nd international symposium on cone penetration testing, CPT’10,
California, USA, Paper ID 2-53.
Meyerhof, G.G. 1956. Penetration tests and bearing capacity of cohesion less soils. Proc. SM1, (82):1-19
M.D. Boone,Bechtel, San Francisco, CA, USA, W.P. Duffy ,Bechtel, London, UK ,M.R. Lewis,Bechtel, Augusta, GA, USA3rd International Symposium on Cone Penetration Testing, Las Vegas,
Nevada, USA - 2014,The use of the CPT in deltaic deposits in Northern Africa
Mostafa Abdou Abdel Naiem Mahmoud, “Reliability of using standard penetration test (SPT) in
predicting properties of silty clay with sand soil “INTERNATIONAL JOURNAL OF CIVIL AND
STRUCTURAL ENGINEERING, Volume 3, No 3, 2013.”
Paul W. Mayne, U.S.A.” Enhanced geotechnical site characterization by seismic piezocone
penetration tests” Invited Lecture, Fourth International Geotechnical Conference, Cairo University,
January 2000, pp. 95-120.
Robertson, P.K.

and K.L. Cabal 2010, “Guide to Cone Penetration Testing for GeotechnicalEngineering”.
Robertson, P.K 2012.Cone penetration test (CPT)-based soil behavior type (SBT) classification
system an update.
Robertson, P.K. Campanella, R.G. & Wightman, A. 1983.SPT CPT Correlations. J. Geotech.
Engrg., 109(11): 1449-1459.
Robertson, P.K.&Campanella, R.G.1985.Liquefaction Potential of Sands Using the CPT. J.
Geotech.Engrg., 111(3): 384-403.
Robertson, P.K.&Campanella, R. G. 1983.Interpretation of cone penetration tests. Part I: Sand.
Canadian Geotechnical Journal. 20(4): 718-733.
Robertson, P.K., 1990. Soil classification using the cone penetration test. Canadian Geotechnical
Journal, 27(1): 151-158.
Robertson, P.K., 2009. CPT interpretation – a unified approach, Canadian Geotechnical Journal, 46:
1-19
197

Robertson. P.K., Campanella, R.G., Gillespie, D., and Greig, J., 1986. Use of Piezometer Cone data.
In-Situ’86 Use of In-situ testing in Geotechnical Engineering, GSP 6 , ASCE, Reston, VA, Specialty
Publication, pp 1263-1280.
Schmertmann,J.H. 1975. Measurement of in-situ shear strength. In ASCE Specialty Conference on
In-Situ Measurement of Soil Properties. (2): 57-138

198

PART-XIV

EARTHQUAKE IN TRIPURA, 3 JANUARY 2017
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Tasnim Tarannum Isaba
Mehedi Ahmed Ansary199

1. Introduction
Bangladesh lies in a seismically active zone making it extremely vulnerable to major earthquakes.
Two major fault lines run through Bangladesh, one 144 km and the other 370 km from Dhaka.
Bangladesh has experienced several fairly mild earthquakes in the last two decades and two major
ones in the past 100 years. Most of the deadliest earthquakes have happened in the Asian belt in thepast 30 years and thousands of lives have been lost and countries damaged, especially in Iran,Pakistan, China, Indonesia, Japan, Haiti and Turkey. At present, due to the recent disaster in Nepal,
Bangladesh is highly susceptible to the risk of an earthquake.
On January 3 (Tuesday), 2017, a moderate intensity earthquake measuring 5.5 on the Richter scaleoccurred in the North-East and adjoining districts of Bangladesh. According to the Central
Seismological Observatory (CSO) in Shillong, the epicenter of the earthquake is located in Dhalai
district of Tripura, close to Mizoram and the Chittagong Hill Tracts of Bangladesh. The earthquake
was felt for about five to six seconds and tremor was strongly felt across Bangladesh and India.
According to USGS, there were 13 839 866 people living within 100 km (50 miles) and 2 million
were living within 50 km (31 miles).

Figure 1: Map showing the affected areas of earthquake in Tripura on
January 3, 2017200

Table 1: General information of e
RegionIndia-Bangladesh Border Region

Geographic coordinates

24.016N, 92.006E

Magnitude

5.5

Depth

36 km

Universal Time (UTC)

3 Jan 2017 (09:09:03)

Time near the Epicenter

3 Jan 2017 (14:39:03)

Local standard time in Bangladesh

3 Jan 2017 (01:09:03)

Location with respect to nearby cities:
19 km (11 miles) NE of Ambasa, India
35 km (21 miles) S of Kailashahar, India
39 km (24 miles) ESE of Khowai, India
42 km (26 miles) SSW of Dharmanagar, India
166 km (102 miles) ENE of Dhaka, Bangladesh

Intensity and fatalities:
ShakeMap is a product of the USGS
Earthquake Hazards Program which provides

near-real-time maps of ground motion andshaking

intensity

following

significant

earthquakes. These maps are used by federal,stateand local organizations, both public andprivate, for post-earthquake response andrecovery, public and scientific information,aswell as for preparedness exercises anddisaster planning.
For the earthquake on January 3, USGS
issued a green alert for shaking-related
fatalities and economic losses. There is a low
likelihood of casualties and damage.
Figure 2: USGS ShakeMap generated for
India-Bangladesh border region after
i
h k

201

Population

exposuretoearthquake

shaking:
According to USGS, 79,286 thousand people
were exposed to weak shaking (MMI scale of
II to III) and 29, 352 thousand people were
exposed to light shaking (MMI scale of IV).
Figure 2 shows the estimated population
exposure to Tripura earthquake, January 3,
2017. The population exposure is higher ontheBangladeshside,particularlyon

Sunamganj and Moulvibazar districts. Table 2
shows the list of exposed cities of thisearthquake.
Table 2: Selected cities exposed to earthquake
in Tripura on January 3, 2017
Modified Mercalli
Intensity (MMI) Scale

City

Figure 3: Estimated population exposure toearthquake shaking
Population (in thousands)

Ranir Bazar

12

Kamlapur

6

Agartala

203

Ambasa6

Kaliashahar

22

Sylhet237

Dhaka

10,357

Aizawl265

Chittagong

3,920

Imphal

224

Barisal202

2. Impact of the Earthquake
2.1. Primary Hazards
As a result of the earthquake, separate cracks have been appeared on the ground in some placesacross the country including Kamalganj of Moulvibazar. According to the local people of the area,
water and sand were seen coming out of the cracks triggering panic among the villagers. Cracks
were developed in at least 50 places including paddy fields of Kamalganj, playground of Kamalganj
High School, land near upazila land office and Adampur Herengabazar ground. The cracks range
from 10 to 50 feet.

Figure 4: Cracks appeared in the cropland and playground of Moulvibazar
2.2. Secondary Hazards
According to the upazila chairman of Kamalganj in Moulvibazar district, soil liquefaction occurredin some places to some extent after the earthquake event. Walls and electric poles collapsed in
Moulvibazar. Also, a fire was reported in a mobile phone tower in Moulvibazar after the earthquake.
As the earthquake occurred in both Bangladesh and India, some secondary hazards have also been
seen in Tripura. Landslides occurred in a number of places on the remote Chhamanu-GobindabariRoad of Dhalai district. According to the officer-in-charge of state fire service department in Dhalai
and Unakoti districts, landslides occurred in a number of places in a five-km radius along the
Chhamanu-Gobindabari road. A portion of the boundary wall of the fire service office at Unakoti
district had collapsed due to the earthquake.

Figure 5: Fire in a mobile phone tower's control in Moulvibazar town
2.3. Human Causalities
The earthquake was reported to cause 3 deaths and several injuries in both Bangladesh and India. All
the deaths were caused by panic and heart attack. An elderly person died of shock at Jagannathpur
upazila in Sunamganj district. According to the doctor of Jagannathpur Upazila Health Complex, thevictim had a cardiac arrest at home after being frightened by the earthquake. The second victim wasa student studying at 8th grade in Chhatak Cement Factory School. She suffered lethal injuries after
falling from stairs when the quake hit. According to Indian Express, a panic-stricken woman,
identified as 50-year-old Kamalini Kanda of Mayachari village under Kamalpur police station died
due to a heart attack.
Due to the collapse of walls and electric poles in Moulvibazar, at least 115 persons were injured as
walls collapsed on them. Four people were seriously injured as they were hit by bricks and brickbats
of walls and by electric poles when they collapsed during the earthquake. The injured were
undergoing treatment at Moulvibazar Sadar hospital.
2.4. Impact on Infrastructure
According to the local people, the earthquake caused damages to the land, roads and buildings ofboth Sunamganj and Moulvibazar district. Many roads of the Kamalganj upazila including
Kumrakapon area were broken and cracks have been spotted in roads of Ranirbazar area. According
to Kamalganj Municipality Mayor, there were cracks in more than 150 buildings, including themunicipality office. Cracks were also observed in the newly constructed upazila auditorium, a threestoried restaurant building at Shamshernagar and a state-run orphanage at Sreemangal. Some parts ofwalls and ceiling collapsed as well while the front veranda caved in by about 1.5 feet. The buildingof Grand Sultan Tea Resort and Golf Plaza were mildly damaged. According to Kamalganj upazila
executive officer, the cracks developed were as long as 40 feet at some points. Public Work

Department officials have already visited the building and reported that the buildings are fine rightnow but further damage cannot be ruled out if another earthquake occurs. Reports from Moulvibazar
said that many half-brick houses were damaged in the tremor and cracks were developed in morethan two hundred buildings. In Tripura, one bridge also developed cracks in Dhalai district.

Figure 6: Cracks developed in buildings of Kamalganj upazila in
Moulvibazar after the earthquake
2.5. Impact on Properties
Cracks appeared in the house of many people. Traders have suffered losses as well due to theearthquake. Glass and tiles stored in a shop at Bhanugachh Bazar broke into pieces during thetremor. According to the General Secretary of Bhanugachh Poura Bazar Banik Samity, around 20
businesses in that market have incurred losses. While the tremor was felt strongly in Tripura, reportsof the quake being felt have also come in from Meghalaya, Manipur, Mizoram and southern Assam.
Sources in Agartala said that as many as 60 houses were reportedly damaged in Dhalai and thenumber of properties damaged is likely to increase.
2.6. Impact on Power Supply and Telecommunication
Power connections remained suspended for hours in more than one hundred villages as the quake
caused a glitch on the Sreemangal grid. According to the Moulvibazar Palli Bidyut Samity DGM(technical), a jumper got disconnected at the Sreemangal Power Grid during the earthquake. As a

result, power connection was suspended in several areas. However, it resumed after the glitch was
repaired.
2.7. Impact on Human Life
Many of the city dwellers came outside in the streets as there was panic when buildings were shaking
by the earthquake. At least five people, including a Shahjalal University of Science and Technology
student, were injured as they tried to come out of multi-storey buildings in Sylhet during the tremor.
New Age correspondent in Chittagong reported that many people of the port city came out of houses
as they felt the quake. In Sylhet metropolis, at least three people sustained minor injuries during
stampede in different parts of city when the earthquake began.
3. Lessons Learned
According to the scientists, Bangladesh is highly vulnerable to earthquake due to its geographicallocation. Bangladesh is positioned at the juncture of several active tectonic plate boundaries and is
one of the most tectonically active regions in the world. It sits where three tectonic plates meet: theIndian Plate, the Eurasian Plate, and the Burmese Plate. Moreover, it sits at the top the world’s
largest river delta at close to sea level, facing both the risk posed by an earthquake and secondaryrisks of tsunamis and flooding in the quake’s aftermath. Although Bangladesh has achieved
considerable success in managing natural disasters like cyclone and flood, researchers have indicatedthat earthquake preparedness in Bangladesh in still inadequate. Unplanned development, highpopulation density, lack of education and safety training as well as poorly constructed buildings inmajor cities have alleviated the earthquake risk in Bangladesh. The collapse of Rana Plaza in 2013
caused the loss of 1,136 lives. Although no major earthquake has occurred in the recent years, thecollapse of Rana Plaza has provided a glimpse of what could happen in the event of a major
earthquake.
The news reports for the earthquake event in Sylhet and Tripura revealed that most of the injuries ofthe earthquake were caused by panic attack and building collapse. People got injured when they were
trying to escape from the building. The response of people in Bangladesh to the earthquake indicatesthat there is a lack of education and preparation about what to do if such an event occurs or how to
be safe during an earthquake. One news report highlighted the fact that people came out of high-risebuildings using the stairs during the shaking of the earthquake. This is incorrect, instead they shouldfind a safe corner of a room or building.
Earthquake damages can be more severe when it is accompanied with poorly constructed buildings.
The news reports indicated that more than 200 buildings were cracked during and after earthquake.
The tilting and cracking of many of these buildings indicated to their weak construction. According206

to experts, Bangladesh is urbanizing rapidly and almost no building conform to the building codes.
Many buildings are constructed by encroaching roads and covering natural waterbodies. Poorly
constructed buildings are also common that are partly built with concrete, bamboo and tin.
Earthquake resistant building construction is not yet considered with proper importance in
Bangladesh. A regular survey should be undertaken to audit integrity of older buildings, major public
highways and bridges to identify vulnerabilities and prevent future damage.
In addition to educating the public, an appropriate gas leakage management system, power supply
control, firefighting, alternative power generation, wireless communication system, heavy equipment
for removing debris and emergency medical facilities are needed to help deal with the aftermath ofan earthquake.

207