Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Seismic Reinforcement for Foundation Utilizing Sheet Piles and Soil
Improvement
Kohei KASAHARA
M. of Eng., Civil Engineering Technology Center, Shikoku Railway Company, Kagawa, Japan
Email: kasahara.kohei.70@rtri.or.jp

Taisuke SANAGAWA
Ph.D., Structures Technology Division, Railway Technical Research Institute, Tokyo, Japan

Hidetoshi NISHIOKA
Ph.D., Structures Technology Division, Railway Technical Research Institute, Tokyo, Japan

Ryoji SASAOKA
Associate Degree, Civil Engineering Technology Center, Shikoku Railway Company, Kagawa, Japan

Yuki NAKATA
M. of Eng., Structures Technology Division, Railway Technical Research Institute, Tokyo, Japan

ABSTRACTThis paper reports a case study of seismic reinforcement for pile foundation of Daisokugawa Bridge in Kagawa prefecturein Shikoku Island. The most popular reinforcement method for the foundation is the additional pile method; however, it
was difficult to adopt this method for Daisokugawa Bridge because some piers were close to the road. Therefore, we
considered the possibility of adopting a reinforcement method utilizing sheet piles that can minimize the area wideningof the footing. In conducting the design, it was necessary to verify that the shear failure would not occur during the Level2 earthquake motion by executing a beam-spring analysis. As a result of the design calculation, this reinforcement method
couldn’t prevent the shear failure of the piles and the footing because the superstructure’s inertial force is large and theliquefaction may occur during the earthquake. In consideration of these circumstances, we adopted a reinforcement
method utilizing sheet piles and soil improvement: improving soil inside the steel sheet piles by the high-pressure
injection stirring construction method. Already, installation of the steel sheet piles, the soil improvement and the
expansion of the footing of two piers have been finished.
Key words: seismic reinforcement, foundation, steel sheet pile, soil improvement, desing

1. Outline of the project

seismic reinforcement project:

the railway sections

1.1. Introduction

between Kojima and Utazu on the Honshi-Bisan Line,

Since Japan may be hit by large earthquakes in the

between Takamatsu and Tadotsu on the Yosan Line (Fig.

near future, seismic reinforcement for structures has been1), and over-road bridges and viaducts intersecting or

carried out all over Japan these days. Shikoku Railway

running side by side with roads designated as emergency

Company has been carrying out seismic reinforcement oftransport roads by municipalities.

railway structures (Kagawa, 2016) based on “theordinanceoftheministerial

concerningThis paper reports the seismic design and theseismic

construction for the seismic reinforcement of foundation

reinforcement of designated railway facilities (Land,

structures of Daisokugawa Bridge in the Honshi-Bisan

Infrastructure, Transport and Tourism, 2013)” (enforced

Line which is the most important railway line in Shikoku

since April 1, 2013). The sections below are subject to thisRailway Company.

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Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

constructed in the river. Therefore, we considered the1.2. Outline of Daisokugawa Bridge
Figs. 2 and 3 show the view of Daisokugawa Bridge.

possibility to make the seismic reinforcement for the

Daisokugawa Bridge is separated into two bridges for the

middle pier unnecessary by apportioning the inertial force

outbound and inbound lines. Each bridge consists of aof the middle pier among the other piers on the land. We

four-span continuous prestressed concrete box girder andcarried out a dynamic analysis of the bridge using a three-

five reinforced concrete piers and cast-in-place concrete

dimensional beam-spring model (Fig. 4). The input

piles. Furthermore, the pier heights for the outbound lines

seismic wave was earthquake motion waves based on theare ranged from a minimum of 19.75 m to a maximum of

hypothesis that the earthquake occurred somewhere along

22.80 m. On the other hand, the pier heights for thethe Nankai Trough, the Median Tectonic Line or theinbound lines are ranged from a minimum of 8.95 m to ahidden faults. The results of the dynamic analysis showedmaximum of 15.35 m.

that if we carried out the seismic reinforcement for the

The result of simplified seismic diagnosis showedpiers on the land to increase the superstructure’s inertialthat these bridges needed seismic reinforcement, however,force affecting the piers on the land, it would turn out toit was difficult to carry out seismic reinforcement for thisbe unnecessary to carry out the seismic reinforcement forpier from the perspective of the workability, cost andtheconstruction period because the middle pier was

superstructure’s inertial forces affecting the piers on the

middle

one

(Fig.

5).

However,

since

the

Honshi-Bisan Line
Yosan Line

Daisokugawa Bridge

The Median Tectonic Line
The Nankai TroughFig. 1

Map of Honshi-Bisan Line and Yosan Line

Fig. 2

Full view of Daisokugawa Bridge- 556 -

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

land increase, the seismic diagnosis showed the risk of theshear failure of pier bodies and piles and the failure of

2. Outline of the sheet pile reinforce method
The sheet pile reinforce method is a seismic

bearings.

reinforcement

methodfor improving the seismic

Therefore, we decided to carry out the seismic

performance of the foundation structure by installing steel

reinforcement with carbon fiber sheets for pier bodies andsheet piles into the ground around the footing andrestrainers for bearings. Additionally, since the burden ofconnecting the steel sheet pile to the footing (Fig. 6). The

the foundation on the land will increase and these bridges

specifications of the method such as the steel sheet pileare long-span bridges, we decided to carry out the seismic

length should be decided by design calculations, and thereinforcement for the foundation in consideration ofembedded depths are relatively short (about the same as

restorability (Supervised by Railway Bureau, Ministry of

the footing width) under general conditions. Therefore,

Land, Infrastructure, Transport and Tourism, edited bythis method is superior in terms of workability. Since theRailway Technical Research Institute, 2012). Even thoughadditional footing dimension can be reduced (up to about

the most popular reinforcement method for the foundation1m), it is suitable for use at locations where land usage isis the additional pile method, it was difficult to adopt thisseverely restricted. Some studies have been carried out

method because some piers (2P, 4P, and 5P) were close tobased on the model experiments, the numerical analysis,roads. Therefore, we considered the possibility to adopt aand so on. Furthermore, the design and construction

reinforcement

piles

manual has been prepared (Supervised by Railway Bureau,(hereinafter called “sheet pile reinforce method”) which

Ministry of Land, Infrastructure, Transport and Tourism,

methodutilizing

steel

sheet

can minimize the widening of the footing.

Fig. 3

Side view of Daisokugawa Bridge

Apportioning the superstructure’s inertial force
Superstructure
上部工(elastic)（弾性）

Bearing spring
支承ばね(elastic, bidirectional)（弾性.2方向）

1P

5P

Reactionforce
隣接桁反力相当
next bridge girder

2P

3P

4P

4P

3P

H.W.L=1.824

2P

Rigid zone 1P
剛域

Pier:く体：部材モデル
member model (M - θ property)（M-θ特性）
基礎：SRばね（2方向）Foundation:
SR spring(bidirectional)

Fig. 4

Carrying out the seismic reinforcement

Overall system frame analysis

Fig. 5- 557 -

Design concept of apportioning
the superstructure’s inertial force

5PProceedings of the First International Conference on Press-in Engineering 2018, Kochi

edited by Railway Technical Research Institute, 2012)
based on the knowledge obtained from these studies.
Since this method is not a large-scale reinforcement,
it has often been used in the cases where ground conditions
are relatively good until now. However, some studies havealso been conducted regarding the reinforcement effects
on pile foundations located in the soft ground and theliquefiable ground in recent years. Sanagawa, et al.
prepared a one-sixth model of the pile foundation, andthey

conducted

theexperiment

on

the

seismic

performance of the sheet pile reinforce method onliquefiable ground (Sanagawa, et al., 2017). This
experiment was conducted under two different kinds ofconditions by changing the specifications of the structure
and input waves: one was a case where it was mainly

Fig. 6influenced by the ground deformation, and the other was

Sheet pile reinforce method

a case where it was mainly influenced by the inertial force.

concrete piles with the sheet pile reinforce method in

Additionally, the steel sheet pile was embedded in the non-terms of costs and space required at the period ofliquefiable layer in both conditions.

construction. In conducting the design calculation, we

As a result of this experiment, in the former case, thedecided that the required performance was safe against thedisplacement of the model structure of the pile foundation

Level 2 earthquake motion (Supervised by Railway

was smaller than the sheet pile reinforce method. As a

Bureau, Ministry of Land, Infrastructure, Transport andresult, it was assumed that the ground flew between the

Tourism, Edited by Railway Technical Research Institute,piles because the resistance area (projected area of the2012): verification about the vertical load and the tensile

horizontal direction) of the pile was small. Furthermore, itload at the pile head, the maximum response horizontal

was given as one of the reasons that the steel sheet pile

displacement at top of the footing, the maximum response

was received the ground deformation directly because theangle of rotation at the top of the footing, the failure ofresistance area of the steel sheet pile was large.

members (the pier body, the footing and the pile).

On the other hand, in the latter case, the displacement

The design calculations were conducted according toof the model structure of the sheet pile reinforce method

the design standards for railway structures (Supervised by

was smaller than the pile foundation. As a result, it was

Railway Bureau, Ministry of Land, Infrastructure,assumed that the vertical resistance of the steel sheet pile

Transport and Tourism, Edited by Railway Technicalsuppressed the rotation of the structure.

Research Institute, 2012) and the design/construction

In the case of Daisokugawa Bridge, since this bridge

manual of sheet pile reinforce method (Railway Technicalwas on the liquefiable ground and the superstructure’s

Research Institute, Obayashi Corporation, Nippon Steelinertial force was strong, we assumed that this bridge

and Sumitomo Metal Corporation, 2016). In particular, thecorresponds to the latter case. For this reason, we

response value was calculated from the nonlinear static

considered whether the sheet pile reinforce method can beanalysis using the beam-spring model and from theadopted or not for the seismic reinforcement based on the

nonlinear response spectrum method (Supervised byknowledge

Railway Bureau, Ministry of Land, Infrastructure,obtained

from

the

abovementioned

experiments.

Transport and Tourism, Edited by Railway TechnicalResearch Institute, 2012). The results of the design

3. Outline of the seismic design
The following is the outline of the seismic design. We

calculations showed that the general sheet pile reinforce

compared the additional pile method for cast-in-place

the footing. As a result, it was assumed that themethod could not prevent the shear failure of the piles and- 558 -

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

superstructure’s inertial force was too strong and the

For a pier 5P, it was found that the distance between the

suppressing effect of the rotation of the structure by thepier for the inbound line and that for the outbound line wassteel sheet pile was not enough when the liquefaction

very short and piles could only be installed in the direction

occurs. To ensure the applicability of the method to theto expand the footing in parallel with the line even if theliquefiable ground, we considered the possibility ofadditional pile method was applied. In this case, because

adopting a reinforcement method utilizing sheet piles andthe scale of the seismic reinforcement would be extremely

soil improvement (Shioi, et al., 2004): the sheet pilelarge, utilizing sheet piles and soil improvement was

reinforce method together with improving soil inside theadopted for cost reasons. Figs. 8 and 9 show the drawing

steel sheet piles by the high-pressure injection stirringof pier 1P and 2P. As can be seen from these figures, if theconstruction method. In conducting the design calculation,

additional pile method is applied, it is necessary to expand

we verified that the shear failure at the pier body, thethe footing. As a result, it is considered that the large

footing, the pile, and the improved soil would not occur
during the Level 2 earthquake motion by executing theTable 2.

Construction process

beam-spring analysis and the FEM analysis.
Table 1 and Fig. 7 show the seismic reinforcement

step

Additional pile method

Utilizing sheet piles
and soil improvement

1

Placing cast-in-place
concrete piles

Installing steel sheet piles

2

Primary excavation

Primary excavation

3

Installing steel sheet piles
for earth retaining

Soil improvement

4

Secondary excavation

Executing shore strut
and waling

5

Pile head treatment

Secondary excavation

6

Driving anchors

Driving anchors

7

Assembling
reinforcing bars

Assembling
reinforcing bars

8

Placing expanded footing

Placing expanded footing

9

Primary backfilling

Backfilling

10

Pulling out steel sheet piles

11

Secondary backfilling

method adopted for the foundation. For a pier 1P, which
was not close to the road, the additional pile method was
adopted for cost reasons. For piers 2P and 4P with strongsuperstructure’s inertial force, utilizing sheet piles and soil
improvement was adopted because the large-scale
reinforcement was required if the additional pile method
was applied, and because the piers were close to the road.
Table 1.
pier
1P
(in/outboundlines)
2P(in/outboundlines)
4P(in/outboundlines)
5P(in/outboundlines)

Results of comparative study

Adopted method

Grounds for
adoption

Additional pile method

Cost

Utilizing Sheet Piles
and Soil Improvement
Utilizing Sheet Piles
and Soil Improvement
Utilizing Sheet Piles
and Soil Improvement

Fig. 7

Cost
Occupation of road
space and cost
Cost

Adopted seismic reinforcement for foundation(Hatching：Additional pile method, Not hatching：Utilizing Sheet Piles and Soil Improvement)- 559 -

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

horizontal force is exerted on the footing by the lateralpiles and soil improvement, we adopted the hat-shaped

flow when the liquefaction occurs.

steel sheet plies which have high joint efficiency and canbe applied at low cost.

4. Construction
4.1. Outline

4.2. State of construction

Table 2 shows the construction process under both

Photos 1, 2, and 3 show construction conditions formethods: the additional pile method and utilizing sheet

the installation of the steel sheet piles at pier 2P. At present,

piles and soil improvement. Regarding the construction

piles are placed at six locations in all at the pier 1P of theunder the additional pile method, because there was anoutbound line, while at ten locations in all at the pier 1P ofapproximately 15m-thick sandy gravel layer in the groundthe inbound line. At pier 2P, the installation of the steel(Fig. 10), the cast-in-place concrete piles were adopted bysheet pile, the soil improvement, and the expansion of thethe full rotation all-caisson method, which can be applied
to the hard ground and can reliably prevent excavationwall collapse. Regarding the construction utilizing sheet
R．L
F．L

LEVEL

R．L LEVEL(mm)

3750 4400 3000 4400 3750
100 100

5500
3000 2000
500

13200

20500

20800

19500

3650 3500 3650
1100 100 100 1100

3.660

3500
100 3000
100 500

3.655

1500 1500
4500
2250

4500

12000

1500 1500
2250

1500
1500
1100 4000 4000 1100
13200

3750

1500 1500
1500 1500
4500 4500
2250
2250
3750
12000
3750

1100

19500
Fig. 8

φ5000

14000
1500 4500 4500 1500
1000
1000

1500 3750 3750 1500

3750

10500

F．L

(mm)

Drawings of the additional pile (1P)

Fig. 9- 560 -

11000
13200

φ3

500

1100

Drawings of the utilizing sheet piles
and soil improvement (2P)

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

footing have been finished for the inbound and outboundlines. Regarding the installation of the steel sheet piles, it
was conducted using “the silent piler (Tauchi, 1999)(Official Website of GIKEN LTD.)” that can be applicableto press-in with augering. At pier 4P and pier 5P,
installation of the steel sheet pile has been finished for theinbound and outbound lines and preparations are being

Groundclassification

N-values
for design

3500

Backfilling
soil

-

3900

Sandy soil

9

14700

made for the soil improvement.

Sandy gravel
layer

29

(mm)

4000

2.48

18600

Sandy soil

37

5800

43000

Liquefaction

G.L.

Cohesive soil

34

Cohesive soil

50

Fig. 10

Geological condition- 561 -

Photo 1.

View of installing steel sheet piles(outbound 2P)

Photo 2.

View of the installed steel sheet piles(inbound 2P)

Photo 3.

View of the soil improvement(outbound 2P)

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Regarding the construction for the outbound line, it

The Ordinance of The Ministerial Concerning Seismic

has been done under a sufficient construction space

Reinforcement of Designated Railway Facilities, The

because the overhead clearance is about 20 m under theOrdinance of the Ministerial of Land, Infrastructure,girders for the outbound line. By contrast, the construction

Transport and Tourism, No. 16, Date of last access Marchfor the inbound line has been done under harsh overhead

23,

clearance restrictions because the overhead clearance

gov.go.jp/search/elawsSearch/elaws_search/lsg0500/detail

ranged from a minimum of 7 m to a maximum of 14 m.

?lawId=425M60000800016. (in Japanese)

Therefore, the piles and steel sheet piles were installed

Dateclearance, and the work was done more carefully tothemachinesfromhittingthe

http://elaws.e-

Official Website of GIKEN LTD. Silent Piler/The Latest Models.

using machines available under the low overhead
prevent

2018,

of

last

access

March

23,

2018,

https://www.giken.com/en/products/silent_piler/.

girders.

Supervised by Railway Bureau. 2012. Ministry of Land,

Furthermore, the displacement of the piers has been

Infrastructure, Transport and Tourism, Edited by Railway

measured by total station at any time during theTechnical Research Institute, The Design Standards forconstruction because this reinforcement work has been

Railway Structures and Commentary (Seismic Design),

carried out for existing railway lines in operation.

Maruzen Publishing Co. Ltd. (in Japanese)Supervised by Railway Bureau. 2012. Ministry of Land,

5. Conclusions
This paper describes the design and construction of

Infrastructure, Transport and Tourism, Edited by Railway

seismic reinforcement for Daisokugawa Bridge. Since

Railwaysome piers were close to the road, we considered theStructures), Maruzen Publishing Co. Ltd. (in Japanese)possibility of adopting a reinforcement method utilizing

Railway Technical Research Institute, Obayashi Corporation,

sheet piles that can minimize the area widening of the

Nippon Steel and Sumitomo Metal Corporation. 2016.

footing. In particular, the response value was calculated

Design and Construction Manual (Draft) of Seismicfrom the nonlinear static analysis using the beam-spring

Reinforcement Method for Existing Railway Foundation

model and from the nonlinear response spectrum method

Structure Using Steel Sheet Piles (Sheet Pile Reinforce

As a result of the design calculation, the general sheet pile

Method), Third edition. (in Japanese)

reinforce method could not prevent the shear failure of the
piles

and

the

footingpresumably

becauseTechnical Research Institute, The Design Standards for
Structures

andCommentary(Foundation

Sanagawa T., Nishioka H., Matsuura K., Higuchi S., Toda K.,

the

Taenaka, S. 2017. Experimental and Numerical Study onsuperstructure’s inertial force is large and the liquefaction

Seismic Behavior of Pile Foundations Utilizing Sheet Pile

may occur during the earthquake.

Reinforcement

In consideration of these circumstances, we adopted

Liquefied

Ground.

Japanese

Geotechnical Journal, Vol. 12, No. 2, pp. 197-210. (ina reinforcement method utilizing sheet piles and soil
improvement to apply the liquefiable ground. Already,inJapanese)
Shioi Y., Segawa N., Inagawa K., Kato K. 2004. Development of

installation of the steel sheet piles, the soil improvement

Seismic

and the expansion of the footing of two piers have been

Improvement for Pile Foundation. Proceedings of the 7th

finished. In the near future, the expansion of the footing at

symposium on ductility design method for bridges. (inpier 1P and the soil improvement work at piers 4P and 5P

Japanese)will be executed. Therefore, we intend to proceed with thisReinforcement

MethodUtilizing

Soil

Tauchi H. 1999. Silent Piler and Press-in Method (Press-in

project with due full consideration for safety.

Construction

Technology

Originatedin

HydraulicPressure). Hydraulics & Pneumatics, Vol. 38, No. 3, pp. 914, Japan Industrial Publishing Co. Ltd. (in Japanese)

References
Kagawa, K. 2016. Seismic Reinforcement by Shikoku Railway
Company, in The Journal of Japan Railway Civil
Engineering Association, Vol. 54, Japan Railway Civil
Engineering Association. (in Japanese)
Ministerial of Land, Infrastructure, Transport and Tourism. 2013.

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