Volume 4, Issue 4 December 2019

Reports

11th IPA Press-in Engineering Seminar in Tokyo 2019 (Continued)(1) Recommendations by JGS against the problems on foundation Pile
Naoki Suzuki
IPA Secretariat
Dr. Hiroshi Furuya gave a lecture on the JGS activity related to "Tilting Yokohama condo case" and introduced somerecommendations on foundation pile made by a JGS special committee. "Tilting Yokohama condo case" was acontroversial case of piling foundation, where several residents found a tilt between the two buildings, and they pointed
out that "A handrail part of the corridor connecting the West Building and the Central Building was out of alignment by
20 mm". Subsequent investigations revealed that 8 piles did not reach the bearing layer, 2 piles did not have enough pilelength, and data of other 45 piles were falsified. as is schematically illustrated in Fig.1. This scandal was taken up
extensively by mass media such as newspapers and television, and widely spread to the public.
Dr. Furuya pointed out the following four issues from the investigative activity;
1)

2)

3)

4)

Chronic problems in the contract work: Construction sequence of pile foundations typically follows as geotechnicalinvestigation, design, building confirmation, and selection of contractors. Generally, engineers in charge do not want
to alter the initial design to meet the deadline of the pre-determined schedule, which might cause some delay. This
problem often results that enough soil investigation is not carried out.
Lack of sharing topographical and geological information: Presently a data base of geological information covering
most urban region in Japan is readily available to engineers for free. The ground under the tilting Yokohama building
has a complex topography with uneven baring layer. If the existing data available were properly referred to, the initialdesign of pile foundations could have been made with higher accuracy.
Lack of knowledge on guideline concept: Guidelines or/and manuals for piling design and construction are aimed, inprinciple, to be written in such a way that everyone could reach the same results. However, for simplicity, theseguidelines and manual sometimes omit the details such as preconditions and leave a room for engineers to interpret.
Some practical engineers are lack of proper knowledge on soil investigation methods and interpretation of theresults.
Lack of geotechnical engineers: A site supervisor familiar with the geotechnical engineering does not always manage
constructions.

Various topics were presented through this lecture. The author has a comment on the use of construction data which
will make it easier to check uncertainties during and after construction due to complex terrain. , and also the author feelsthat engineers will have to keep in mind that new technologies are likely to be a black box, thus causing data falsification
more easily. It will become more necessary for us to keep up with new technologies and understand their ideas than everbefore.
Maximum deviation of 2.4 cm

Crossing corridor

Piles

About 10 m

Fig.1. Illustration of "Tilting Yokohama condo case"(https://www.sankei.com/)24

Photo 1. Dr. Furuya was giving a lecture

Volume 4, Issue 4 December 2019

Reports

11th IPA Press-in Engineering Seminar in Tokyo 2019 (Continued)(2) Use of press-in piling data for estimating subsurface information:
IPA-TC2 technical material
Yukihiro Ishihara
Manager, Scientific Research Section, GIKEN LTD. / Director, IPA
IPA-TC2 (Chaired by Dr. Osamu Kusakabe, President of IPA) finalized a Japanese technical material on the use of press-in
piling data for estimating subsurface information in 2017, titled as ‘Technical Material on the Use of Piling Data in thePress-in Method, I. Estimation of Subsurface Information’. This technical material was published by IPA and is accessible
on IPA Website. This report overviews the research activities on the use of press-in piling data, which were presented in
IPA Press-in Engineering Seminar in Tokyo.
1. BackgroundThe design and construction of structures with piles are usually based on the subsurface information that are obtainedby interpolating the results of the site investigation results carried out separately from each other with the distance ofseveral dozens of meters or about one hundred meters. On the other hand, local variations are often found in the actual
ground conditions, such as the inhomogeneity of the soil layers and the existence of weak soils or hard cobbles in the
ground. The difference between the prior information and the actual conditions arising from the inhomogeneity of theground is one of the major factors that deteriorate the rationality of design and construction of structures with piles.
Besides the well-known features of the Press-in Method (low noise, low vibration, spatial efficiency etc.), a feature of an
automatic acquisition of piling data for each single pile has been focused on by Giken research team, in the expectationof rationalizing the design and construction of piles.
2. Estimation methods
So far, methods of estimating subsurface
information from piling data have beendeveloped for three different installation
techniques in the Press-in Method: Standard
Press-in (without any installation assistance),
Press-in with Augering (Crushpiling) and Rotary
Cutting Press-in (Gyropiling). These estimation
methods do not require any instrumentation
with piles, but assume several conditions aslisted in Table 1.

Table 1 Assumed conditions in the estimation methods
Installation techniques
Assumed conditions
1) Without interlock connection
Standard Press-in2) With repeated penetration and extraction
3) Relatively small penetration rate
Press-in with Augering
1) Piling data during pre-augering process(Crushpiling)2) Requirement in size and shape of auger head
Rotary Cutting Press-in
1) Measurement of the length of soil inside the(Gyropiling)pile

In Standard Press-in, the penetration of a pile is similar
to that of a cone in CPT. This similarity is taken into
account in the estimation method. The estimation
process can be divided into four, as shown in Fig. 1(Ishihara et al., 2015a). Firstly, the vertical jacking force
applied to a pile by a press-in machine is decomposed
into a base resistance (Qb) and a shaft resistance (Qs).
Qb is obtained as the difference between the jacking
forces measured when the pile base passes a certain
Fig. 1. Estimation process in Standard Press-in
depth for the first time and for the second time in eachcycle of the repeated penetration and extraction(Ogawa et al., 2012). Secondly, a unit base resistance (qb) and a unit shaft resistance (qs) are obtained from Qb and Qs, byconsidering the area on which Qb and Qs are acting. The plugging conditions are taken into account to define the effective
base area by introducing IFR (Incremental Filling Ratio) for tubular piles (Lehane & Gavin, 2001; Ishihara et al., 2018), andthis is extended to sheet piles considering the shape effect (Taenaka, 2013). Thirdly, the obtained qb and qs are converted
into CPT qc and fs, by considering the scale effect on the plunging values of qb (White & Bolton, 2005) and the rate effectbased on the Finnie factor (Finnie et al., 1994; White et al., 2010; Bolton et al., 2013). Finally, the soil type and SPT N are
estimated from qc and fs, based on the methods developed by Robertson (1990) and Jefferies & Davies (1993) respectively.
25

Volume 4, Issue 4 December 2019
In Press-in with Augering, two estimation methods were proposed (Ishihara et al., 2015a), based on the knowledge
acquired in the field of rock drilling. The first one is to estimate SPT N from a torque on the auger head (Tb), a penetration
rate (vd) and a rotation number (n) as shown in Eq. (1), with A and γ being constants. This is based on the knowledge thatthe parameter Tb/(dc)γ, where dc is the depth of cut (= vd/n), is proportional to the unconfined compressive strength of arock (Nishimatsu, 1972; Fukui, 1996; Fujimoto, 2005) and the assumption that the unconfined compressive strength and
SPT N are in proportional relationship. The second one is the method known as MWD (Measurement While Drilling) (JGS,
2004), in which SPT N is estimated from Tb, vd, n and a base resistance on the auger head (Qb) as shown in Eq. (2), with
Cn the constant.
N=A

Tb(vd ⁄n)γN = Cn (Qb + 2π

(1)
Tb
)
vd ⁄n

(2)

The estimation process in Rotary Cutting Press-in is divided into
three, as shown in Fig. 2. Firstly, a vertical and a rotational jacking
forces applied to a pile by a press-in machine (Q, T) aredecomposed into base and shaft components (Qb, Qs, Tb and Ts),by introducing Eqs. (3) - (6) where δsp, Do and vr are the frictional
angle at the soil-pile interface, the outside diameter of the pileand the rotational rate of the pile shaft, respectively (Ishihara etal., 2015b).
Q = Qb + Qs
T = Tb + Ts
Tb tanδsp=
DoQb
3
Ts vr ⁄vd
=
Do
Qs
2

Fig. 2. Estimation process in Rotary Cutting Press-in

(3)
(4)
(5)
(6)

Of these, Eq. (5) is based on the assumption that both Qb and Tb
are expressed by a unit base resistance (qb), while Eq (6) is obtainedby assuming that a frictional stress on the pile is shared by Qs and
Ts according to the ratio of vd to vr. The validity of the latterassumption is discussed by Bond (2011). Secondly, the incremental
energy (δE) required for deforming a soil below the pile base by a
volume of δV is calculated from Qb and Tb. δE/δV is an index called
Specific Energy, which is widely used to represent the performanceof machines for rock drilling (Teale, 1965; Hughes, 1972). According
to Hughes (1972), Li & Itakura (2012) and others, there is a linear
correlation between the Specific Energy in rock drilling and theunconfined compressive strength of the rock. By extending it, theSpecific Energy required for penetrating something into a ground
may be assumed as being in proportion to the unconfinedcompressive strength of the ground. By considering the
proportional relationship between the Specific Energy required for
Rotary Cutting Press-in and that for the penetration of an SPT
sampler, SPT N value is obtained.
3. Case studies
Fig. 3 is the comparison between the subsurface information
obtained by SPT and that estimated from the piling data inStandard Press-in, where a closed-ended tubular pile with Do =318.5mm and a sheet pile with the width of 600mm were pressedin at vd = 20mm/s and 30mm/s respectively. The peak values of N
26(a) Closed-ended, Do = 318.5mm, vd = 20mm/s(C11-05)(b) Sheet pile, 600mm wide, vd = 30mm/s (J0617-05)
Fig. 3. Comparison of SPT & boring (left) and estimation(right) (Standard Press-in)Volume 4, Issue 4 December 2019
and the soil type are well estimated, while the values of N (otherthan the peak values) are underestimated. The previous casestudies including these two have revealed that the effect ofplugging condition on the estimated results is significant while theeffect of penetration rate is not. Fig. 4 is the comparison between
the subsurface information obtained by SPT and that estimatedfrom the piling data in the pre-augering process in Press-in with
Augering, using an auger head with the number of wings of three
and the outside diameter of 450mm. The trend of the variation of
N with depth is well estimated, while big differences are found atsome depths. Through the case studies including this, thesedifferences are believed to be associated with the existence oflarge gravels or stones, judging from the records in SPT. Fig. 5 is thecomparison between the subsurface information obtained by SPT
and that estimated from the piling data in Rotary Cutting Press-in.
The trend of the variation of N with depth is well estimated in thiscase, where the plugging condition were confirmed as almost
constant with depth. Another other case study, on the other hand,
has clarified that the effect of the plugging condition on theestimated results is significant. If the plugging condition varies
with depth, it is recommended to measure the length of the soilcolumn inside the pile with a sufficient frequency of data samplingso that IFR can be estimated continuously with depth.

Fig. 4. Comparison of boring (left), SPT and estimation(right) (Press-in with Augering)

4. Practical use of the estimated results
Based on the discussion through case studies, the technicalmaterial recommends that the estimated results should be
limitedly used as reference information in termination control ofpiling work (e.g. confirmation of the bearing stratum), judgementof alteration of installation techniques, and so on, at the moment.
Three examples are mentioned as follows. 1) Contractors grasp
the trend of variation of the estimated N with depth and confirm
the bearing stratum. They propose an alteration of theFig. 5. Comparison of boring & SPT (left) andembedment depth, if significant variation in the depth of bearing
estimation (right)
stratum. 2) Contractors alter the press-in conditions (to operate(Rotary Cutting Press-in)press-in machines) based on the estimated information andimprove the efficiency of piling work. 3) Contractors summarize the estimated information and propose an alteration inconstruction plan (e.g. re-selection of installation assistance) when unexpected ground conditions are encountered.
It is also recommended in the technical material that additional subsurface investigations should be conducted if thevalidity of the estimated results is dubious due to a significant difference from the existing subsurface information. In
such a case, however, the limitation in the applicability of SPT to a hard ground (Mitsuhashi, 1995; Ogawa et al., 2013)
have to be considered. Other options could be a trial digging or a large-diameter core tube sampling (Watanabe et al.,2006). A ground-penetrating radar (Kimura et al., 2000) or a surface-wave method may also be the options if their present
technical limitations (difficulty in classifying cobbles and cavities in the former and low dissolution in the latter) areovercome.
5. Future challenges
The author expects the estimation techniques to be practically used in actual construction projects. At the same time,
continuous efforts are necessary on (1) updating the values of parameters by accumulating estimation results, (2)removing some of the restrictions in table 1 or developing new estimation methods, (3) direct estimation of pileperformance, (4) developing better measurement techniques, and so on, to further sophisticate these techniques. Dueto the uncertainties related with the ground, the concept of Observational Method addressed by Terzaghi (Peck, 1969) is
still effective in the present construction projects; design calculations are still a sort of assumption that requires
confirmation or modification during the construction phase (Kusakabe, 2017). The author expects that the estimation
techniques assure a firm step forward for the press-in piling industry in this context. An English version of the IPA-TC2
technical material are to be prepared in the near future.

27

Volume 4, Issue 4 December 2019
6. References
Bolton, M. D., Haigh, S. K., Shepley, P. and Burali d’Arezzo, F. 2013. Identifying ground interaction mechanisms for pressin piles. Proceedings of 4th IPA International Workshop in Singapore, Press-in Engineering 2013, pp. 84-95.
Bond, T. 2011. Rotary jacking of tubular piles. M.Eng. Project Report, Cambridge University Department of Engineering,
50p.
Finnie, I. M. S. and Randolph, M. F. 1994. Punch-through and liquefaction-induced failure of shallow foundations on
calcareous sediments. Proceedings of International Conference on Behaviour of Offshore Structures, BOSS’94, pp. 217230.
Fujimoto, A., Takenouchi, Y., Ogura, Y., Kobayashi, S. and Haino, H. 2005. Development of rational construction method
for road tunnel junctions. JSCE Proceedings of Tunnel Engineering, Vol. 15, pp. 323-330. (in Japanese)
Fukui, K., Okubo, S. and Homma, N. 1996. Estimation of rock strength with TBM cutting force and site investigation at
Niken-goya tunnel. Journal of the Mining and Materials Processing Institute of Japan (MMIJ), Vol. 112, pp. 303-308. (inJapanese)
Hashizume, Y., Uchida, K. and Kiya Y. 2002. Construction management of bored concrete pile. Proceedings of the 37th
Japan National Conference on Geotechnical Engineering, pp. 1391-1392. (in Japanese)
Hughes, H. M. 1972. Some aspects of rock machining. International Journal of Rock Mechanics & Mining Sciences, Vol. 9,
pp. 205-211.
Ishihara, Y., Ogawa, N., Okada, K. and Kitamura, A. 2015a. Estimating subsurface information from data in press-in piling.
Proceedings of the 5th IPA International Workshop in Ho Chi Minh, Press-in Engineering 2015, pp. 53-67.
Ishihara, Y., Haigh, S. and Bolton, M. D. 2015b. Estimating base resistance and N value in rotary press-in. Soils andFoundations, Vol. 55, No. 4, pp. 788-797.
Ishihara, Y., Kikuchi, Y. and Koseki, J. 2018. Model test on correlation between plugging condition and Incremental Filling
Ratio during press-in on open-ended tubular pile. Proceedings of the 53rd Japan National Conference on GeotechnicalEngineering. (in Japanese) (in press)
The Japanese Geotechnical Society (JGS). 2004. Other soundings. Japanese Standards for Geotechnical andGeoenvironmental Investigation Methods, pp. 329-337. (in Japanese)
Jefferies, M. G. and Davies, M. P. 1993. Use of CPTu to estimate equivalent SPT N60. Geotechnical Testing Journal, GTJODJ,
Vol. 16, No. 4, pp. 458-468.
Kimura, M., Nakamura, H. and Abe, H. 2000. The case to have confirmed the cavity which is in the cobblestone mixture
gravel bed using the underground radar. Proceedings of the 35th Japan National Conference on GeotechnicalEngineering, Vol. 35, No. 1, pp. 427-428. (in Japanese)
Kusakabe, O. 2017. Preface. Technical Material on the Use of Piling Data in the Press-in Method, I. Estimation of
Subsurface Information, 2p.
Lehane, B. M. and Gavin, K. G. 2001. Base resistance of jacked pipe piles in sand. ASCE Journal of Geotechnical andGeoenvironmental Engineering, Vol. 127, No. 6, pp.473-480.
Li, Z. and Itakura, K. 2012. An analytical drilling model of drag bits for evaluation of rock strength. Soils and Foundations,Vol. 52(2), pp. 206-227.
Mitsuhashi, K. 1995. Know-how of Reading and Utilizing Boring Data to Prevent Troubles, 208p., Kindaitosho, 1995. (inJapanese)
Nishimatsu, Y. 1972. The mechanics of rock cutting. International Journal of Rock Mechanics and Mining Sciences &Geomechanics, Vol. 9, Issue 2, pp. 261-270.
Ogawa, N., Nishigawa, M. and Ishihara, Y. 2012. Estimation of soil type and N-value from data in press-in pilingconstruction. Testing and Design Methods for Deep Foundations, IS-Kanazawa 2012, pp. 597-604.
Ogawa, N., Okada, K. and Ishihara, Y. 2013. Estimation of N value from PPT data in press-in with augering. Proceedings of
the Annual Conference of Shikoku Branch of the Japanese Geotechnical Society, pp. 57-58. (in Japanese)
Peck, R. B. 1969. Advantages and limitations of the observational method in applied soil mechanics. Geotechnique, Vol.
19, No. 2, pp. 171-187.
Robertson, P. K. 1990. Soil classification using the cone penetration test. Canadian Geotechnical Journal, 27, pp. 151-158.
Taenaka, S. 2013. Development and optimisation of steel piled foundations. Ph. D. thesis, The University of Western
Australia, 289p.
Teale, R. 1965. The concept of specific energy in rock drilling. International Journal of Rock Mechanics & Mining Sciences,Vol. 2, pp. 57-73.
Watanabe, K., Araki, K. and Endo, M., 2006. Cobble or pebble survey method, Micro Sampling Method Research
Organization, 10p. (in Japanese)
http://www.microsampling.org/download/report_2006_JSTT.pdf
White, D. J. and Bolton, M. D. 2005. Comparing CPT and pile base resistance in sand. Proceedings of the Institution of
Civil Engineers, Geotechnical Engineering 158, pp. 3-14.
White, D. J., Deeks, A. D. and Ishihara, Y. 2010. Novel piling: axial and rotary jacking. Proceedings of the 11th International
Conference on Geotechnical Challenges in Urban Regeneration, London, UK, CD, 24p.
28

Volume 4, Issue 4 December 2019

Reports

11th IPA Press-in Engineering Seminar in Tokyo 2019 (Continued)(3) Improvements of Practical application of estimation method of groundinformation using Press-in datai) Expansion of the usage of estimation of ground information during press-in withaugering
Koichi Okada“Silent Piler” pushes a pile into the ground by static loading,and the press-in force and penetration depth can berecorded during press-in. We call these measurement data
“Press-in data”. These data have been often used by piler
operators for checking piling work and by Client for
managing quality of piling. Moreover, “Press-in data”
contains valuable information such as ground information.
Fig.1 illustrates the “Press-in Data Monitoring System” using
Press-in data. This system features two new technologies:
First is automatic piling to optimize piling work. This system
can optimize the piling work automatically by using Press-in
data for estimating ground conditions. Second is estimationof ground information such as N value or soil classificationby using Press-in data. In the actual ground. If we use thissystem, it will become easier to confirm the bearing stratum
or check the construction plan because we can obtain thedata from all the piles.
We have been using Press-in Data Monitoring System since2013. Although current Press-in Data Monitoring System
has some limitations on scope of application (Table.1), it
was confirmed that automatic operation by Press-in Data
Monitoring System saved the piling time up to 30%.
Laborsaving and productivity improvement were confirmedin some construction sites. Estimation of groundinformation by Press-in Data Monitoring System is graduallyused for reference of changing construction method.

Chief, Construction Solutions Development Department
GIKEN LTD.

Fig.1. Press-in Data Monitoring System

Standard
Press-inPress-inwithaugering

Press-inwith rotary
cutting①Optimization ofpiling－✔

－②Estimation ofground information

✔

✔

✔

Table.1. Scope of application of Press-in Data
Monitoring System

In Japan, Ministry of Land, Infrastructure and Transport promotes “iConstruction” for laborsaving and productivity improvement. Press-in Data
Monitoring System can be selected to one of the possible solutions for these
movements. For example, it is possible to achieve uniformity in operation speed
in foreign countries where there are few experts who could operate the silent
piler.
In the estimation method of ground information, N value can be estimated inpress-in with augering (Fig.2) (IPA,2017). However, there is a limitation that thisestimation method can only be used in a specific shape of auger. This is a problem
because other shapes of auger are often used in construction sites. We devised
the method that can estimate N value with any shapes of auger by using
correction coefficients for each auger shape (Okada et al., 2018).
29

Fig.2. Press-in with augeringVolume 4, Issue 4 December 2019

Auger shape is very complicated, so we simply modeled
Auger shapes by diameter and number of wings (Fig.3).
For the torque 𝑇𝑇 generated on this modeled, the auger
shape can be expressed eq.1,
1

𝑇𝑇 = 𝑁𝑁𝑤𝑤 ∗ 𝑞𝑞𝑏𝑏 ∗ 𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 ∗ 𝑅𝑅 2 𝐿𝐿 ⋯ (eq. 1)
2

Here, 𝑁𝑁𝑤𝑤 : number of wing, 𝑞𝑞𝑏𝑏 : unit base resistance,𝛿𝛿: wall friction angle, 𝑅𝑅: diameter of auger, 𝐿𝐿:width ofwing. According to this equation, it is possible to usesame estimation method by correcting torquegenerated from other auger shapes into that is
generated by a specific shape of auger.

Fig.3. Model of Auger head shape

In order to check the validity of this correction, a fieldtest was conducted with many types of auger shape inthe same site and N values were estimated from pressin data (Fig.4). These graphs show that estimated N
values without correction vary greatly. On the contrary
the estimated N values with correction do not varylargely and are similar to N values in this site. It meansthat the correction is considered to work as assumed. In
the future, we will work for practical use of estimation
method by conducting validation of this correction indifferent types of ground.
Fig.4. Comparison of Estimated N values
References
International Press-in Association (IPA), 2017, Technical material on the use of piling data in the Press-in Method Ⅰ.
Estimation of subsurface information, pp 33-39. (in Japanese)
Okada. K., Ogawa. N. and Ishihara. Y., 2018, Case Study on Estimation of Ground Information with the Use of Construction
Data in Press-in Method, ICPE 2018, pp 371-378.

ii) Expansion of the usage of estimation of ground information during press-in withStandard Press-in Method
Nanase Ogawa
GIKEN LTD.
1.

Estimation of subsurface information and issues in the standard press-in Method

In standard press-in, a pile is installed by a static jacking force in soft ground with N-value of 25 or less. This technique
has used a series of down and up movement with hydraulic cylinders to install a pile/sheet pile. The mechanism to installa pile/sheet pile is similar to that of a Cone Penetration Test (CPT), so cone resistance (qc) and shaft resistance are
estimated from the press-in force, and the estimation method of N-value and soil classification has been established1).
In the case where the standard Press-in method is used to estimate subsurface information, the condition needs thePress-in data acquired in the state which the interlocks disconnected. Under this condition, after estimating data inwithout interlock, it is necessary to pull out the steel sheet pile, and reconstruction in with interlock, which will increase
the time required compared to normal construction. It is an important issue to remove the condition without interlocks
in order to reduce the time and to increase the number of working examples.

30Volume 4, Issue 4 December 20192.

Verification for solving problems

In cases where the steel sheet pile constructed with interlock, theevaluation of the interlock resistance becomes a problem. Theinterlock resistance refers to the resistance generated along theinterlocking part between a reaction pile and an installation pile.
Fig. 1 illustrates an image of installation and extraction operations
with interlock. Fig. 1-(1) shows the initial installation, the pile headload (Q1) at the time consists of tip resistance (Qb), shaft resistance(Qs) and joint interlock resistance (Qi). After installation in thepredetermined length, it immediately turns into extraction
operation, and extracted the predetermined length, and then itturns to installation motion again. Fig. 1-(4) presents the situation
during reinstallation, where the pile head load (Q2) consists of the
shaft resistance (Qs) and the joint interlock resistance (Qi) at early
depth. Therefore, the tip resistance (Qb) during installation can be
estimated from the difference between Q1 and Q2.
Fig. 2 presents the field date, showing that the pile head loads areplotted with depth for the cases with and without interlocks.
Obviously, the head load with interlock is larger than without one.
The difference is considered to be the value of resistance between
interlock. Fig. 3 shows the results of CPT index which are themeasured value, and estimated results from Press-in data. The
estimation results are similar to the measured one that the changewith depth can be estimated, like the value are larger in sandy layer
at 4-6m depth than other depths. However, all the peak values areevaluated small. The estimated N-value shows the similartendency as the estimated CPT index. Fig. 4 is the estimation
results of subsurface soil profile information. In cases of without
interlock, the soil classification of sandy and cohesive soil isgenerally consistent with the CPT results. On the other hand, in thecase of with interlock, the whole layers have judged to be sandy
soil.
3.

Fig. 1. Resistances and sheet pile baseFig. 2. Press-in force

Summary

The CPT index, N-value and the soil classification were estimatedusing the Press-in data with interlock. In all cases, the trend ofchange with depth could be grasped. In addition, the peak value ofthe cone index and N-value were underestimated, as for the soil
classification, the particle size was evaluated to be larger. In the
future, we will continue to accumulate the Press-in data in orderto improve the practicability of estimation method.

Fig. 3. Cone resistance

4. Reference1）International Press-in Association (IPA), 2017. Technical materialon the use of piling data in the Press-in Method Ⅰ. Estimation of
subsurface information, pp. 7-32. (in Japanese).

Fig. 4. Results of the estimation31

Volume 4, Issue 4 December 2019

Reports

11th IPA Press-in Engineering Seminar in Tokyo 2019 (Continued)(4) Application of the Press-in Data Monitoring system
Masafumi Yamaguchi
IPA Secretariat
The fourth lecturer was Mr Tomohisa Ozawa, President of Ozawa Civil
Engineering and Construction Co. Ltd. which is one of the leading piling
contractors in Japan. He presented an application example of the Pressin Data Monitoring system, where a piling method was changed from avibrator hammer assisted by water jetting to press-in assisted by augering
due to unexpected ground conditions. The purpose of the piling work in
the project was to construct six temporary earth retaining walls ofrectangular shape. Each earth retaining consisted of 14.0-15.5m steel
sheet piles which had to be installed into hard shale whose SPT N value isover 50. At the stage of the tender, a vibratory hammer assisted by water
jetting was specified by the client, which was unlikely to succeed due tothe ground conditions.

Photo 1. Mr. Ozawa was giving a lecture“We encountered some difficulties in changing the piling methodology”
Mr Ozawa said. “First of all, the test piling had to be conducted by the vibratory hammer for all steel sheet piles, eventhough we expected it would not be a success. This was at the direction of the client. It was a waste of time and cost.
Secondly, all bore hole logs had to be re-collected at each temporary retaining wall as proof of the methodology change,
which also extended the construction duration and increased the cost. Thirdly, the client did not have the cost estimate
standard1) of the pressing-in assisted by the augering”. Solving the second issue, the Pile Penetration Total (Hereinafterreferred to Press-in Data Monitoring) system was utilized by Ozawa Civil Engineering and Construction Co. Ltd. The Pressin Data Monitoring system is the latest technology to estimate and record ground condition during pre-boring. By utilizing
this system, the client accepted that there was no need for any additional borehole logs. Furthermore, the client also
approved one or two piling tests by vibratory hammer at each retaining wall instead of all the steel sheet piles after
several meetings and a cost estimate standard2) issued by Japanese Press-in Association to estimate the piling cost.
In conclusion, Mr Ozawa said “Press-in Data Monitoring system was useful, of course. Additionally, the technical material3)
based on the science was important to prove that the latest technology is valid. For the estimation, the cost estimate
standard made by past applications was helpful. They enabled us to logically and smartly discuss with the client and themain contractor based on science, technology and applications.” I think that every participant understood their opinion
and saw massive potential in the system.
1)In Japan, public clients (i.e. Ministry of Land, Infrastructure, Transport and Tourism) use the cost estimate standard to
estimate a piling cost published by themselves or some associations. This client was a private one.
2) Japanese Press-in Association (JPA), 2017. The cost estimation standard of the Hard Ground Press-in Method.
3) International Press-in Association (IPA), 2017, Technical material on the use of piling data in the Press-in Method Ⅰ.
Estimation of subsurface information (in Japanese).

Photo 2. Press-in assisted by augering

Photo 3. The technical book32