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

Experimental Study on Reinforcement of Existing Bridge Pile Foundations
Subjected to Lowering of Riverbed Soil Using Sheet Pile Wall
Tanatan TIKANTA
Civil engineer, Department of Rural Roads, the Ministry of Transportation, Chiang Mai, Thailand

Tatsunori MATSUMOTO
Professor, Graduate School of Kanazawa University, Kanazawa, Japan
Email: matsumoto@se.kanazawa-u.ac.jp

Anh-Tuan VU
Lecturer, Department of Civil Engineering, Le Quy Don Technical University, Hanoi, Vietnam

Shinya SHIMONOTechnician, Kanazawa University, Kanazawa, Japan

ABSTRACT
Development of an effective countermeasure for the existing bridge foundations subjected to the influence of riverbed
excavation in Thailand is the main objective of this study. Due to the riverbed soil excavation for the utilization inconstruction works for many years, the levels of riverbed have been considerably decreased, resulting in reduction ofembedded lengths of piles for bridge foundations. The reductions of pile embedment lengths, in other words, reductionsof bearing capacity due to the lowering of riverbed soil is the main cause of bridge pile foundation settlements or collapses
at present. In order to prevent the damages of existing bridge pile foundations caused by riverbed soil excavation, areinforcement method using sheet piles called “Sheet Pile Wall (SPW) reinforcement” is proposed in this paper. The
proposed SPW reinforcement method consists of 2 simple steps without new additional piles or any modifications ofexisting structures. Firstly, sheet piles are constructed surrounding the existing problematic bridge pile foundation.
Secondly, the empty space inside the SPW is filled with sand or other porous materials such as crushed concrete. In order
to investigate the performance of the proposed SPW reinforcement method, series of load tests on the small sized model
single pile and model 4-pile pile foundation were carried out. The experimental results show that the proposed SPW
reinforcement method is very efficient and promising.
Key words: Reinforcement, Existing bridge, Pile foundation, Riverbed soil excavation, Model load test

1. Introduction
In the past decade, the Mae Nam Ping River crossing

the footing, jacking up the bridge girders and extending

bridges in Chiang Mai and Lamphun, located in thesmooth on the bridge slabs as shown in Fig. 3.

the height of the settled bridge pier by 0.80 m to keep
A few years later, another pile foundation at the piernorthern area of Thailand (Fig. 1), encountered pilefoundation damages frequently.

No.7 of the same bridge LP.010 settled again during a highFig. 2 shows the first case of bridge foundation

flood season in 2010. This time, the settled pile foundation

damage in 2006. One of pile foundations of the bridge

collapsed and fell down into the river within 5 days after

LP.010 in Lamphun settled during a high flood season.

the settlement. The collapsed bridge LP.010 was repaired

The investigation and arrangement for the solution werein 2013 by constructions of two new pile foundations at

performed for 2 years. The settled bridge LP.010 was

new locations on both sides of the previously collapsed

repaired in 2008 by using new additional piles, extending

foundation.

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

In the same year of 2010, two other bridges crossing

The Mae Nam Ping
River in Chiang Mai
and Lamphun area

the Mae Nam Ping River named CM.015 and CM.025 also
encountered the differential settlement problem. Both ofthem were repaired in 2013 by the similar way as therepair of the previous settled bridge (LP.010) in 2008.
The main cause of the bridge foundation damages
mentioned above was the lowering of riverbed soil, inother words, the reduction of pile embedment length.
Though the damaged bridges were repaired, most ofundamaged bridge pile foundations along the river still
have potential risks of being damaged due to the riverbed
soil excavation as shown in Fig. 4.
Although the repairs of the damaged bridge weresuccessful, the repair method could not be applied to theFig. 1

Location of the Mae Nam Ping River in Chiang Mai andreinforcement of undamaged bridge foundations, becauseof a high cost and a long construction time of the repair

Lamphun, Thailand

method in which additional piles and extension of footing
original
riverbed

were required. Hence, in order to obtain an efficient

0.80 mcountermeasure for the existing bridge pile foundations
subjected to the problem of riverbed soil excavation, afundamental experimental study was carried out in this
pier
No.6

paper. Considering safety, economic and uncomplicated

pier
No.5

approach, a reinforcing method using sheet pile wall

pier
No.4

(SPW) called “SPW reinforcement” is proposed in this

0.80 msettlement

study.

LP.010 : constructed in 1995
10 m width, 180 m span length

Fig. 2Differential settlement of the bridge LP.010 in Lamphun,

Thailand (2006)
original
riverbed
free standing
length ofabout 3 mpier height
extension
about 0.8 m

pier
No.4

LP.010 : constructed in 1995
10 m width, 180 m span length

CM.006 : Constructed in 1996
10 m width, 220 m span length
pier
No.5

pier
No.6

Fig. 4

An example case of undamaged bridge which has

potential risk of being damaged (2012)

Fig. 5 illustrates the concept of the SPW

new piles
reinforcement

reinforcement method. The construction procedure of the
SPW reinforcement consists of two simple steps without

Fig. 3

Repair of the settled bridge LP.010 in Lamphun,

Thailand (2008)

new additional piles or any modifications of existing
structures. Firstly, a sheet pile wall is constructed- 100 -

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

surrounding

pile

instrumented along the pile shaft to obtain axial forces,

foundation. Finally, the empty space inside the SPW istheexisting

problematic

bridgeshear forces and bending moments during the load tests.

filled with sand or other porous materials such as crushed

Sand particles of the sand used for the model ground wereconcrete.

glued on the pile shaft to increase shaft friction and toprotect strain gauges from damage. An end cap was not
attached to the pile tip so that the pile had open-ended
condition. Physical and mechanical properties of themodel single pile are listed in Table 1.

V32

sheet pile wall
SG level 1
SG level 1aflood load
flood load

filled
sand

50
20

glued
sand
particles

180

present
riverbed
SG level 2

L1

600 mm

L2

100

600 mmSG level 3
100

Fig. 5 The concept of Sheet Pile Wall (SPW) reinforcement
SG level 4

method100
SG level 5
SG level 6

A method for reinforcing an existing pile foundation
by means of sheet pile wall, called the In-cap Method, has

opened-end

20
30

strain gauge

been proposed by Fukuda et al. (2005). The In-cap methodsurrounds the existing foundation footing to a required

Fig. 6

Configurations of the model pile for single pile load tests

depth, solidifies the inside of the sheet piles for

Table 1.

improvement of the footing and integrates the improved

single pile

Physical and mechanical properties of the modelfooting with the existing foundation.

Aluminium alloy

Type of material

The SPW reinforcement method proposed in thispaper has similar feature to the In-cap Method, however,

JIS A6063

Pile length, Lp (mm)a big difference between the two methods is that there is
no soil (ground) around the sheet pile wall in the SPW
reinforcement method. Hence, investigation of thereinforcement mechanisms in the SPW method wasOuter diameter, Do (mm)32

Inner diameter, Di (mm)29.3Wall thickness, tw (mm)1.35

Density, p (g/cm )2.70

Young's modulus, Ep (MPa)65,400Poisson's ratio, p

0.33

3

carried out in this research.
2. Experimental models
In order to validate the performance of SPW

600

Aluminum pipes of 20 mm in diameter and 285 mm

reinforcement method, series of model load tests on ain length as shown in Fig. 7 were employed as model piles

single pile and 4-pile pile foundation were carried out.

in a 4-pile pile foundation model. Each model pile was
2.1. Model piles and model 4-pile pile foundation
An aluminum pipe of 32 mm in diameter and 600

instrumented with strain gauges and was glued with sandmm in length as shown in Fig. 6 was employed as a model

An end cap was attached to the pile tip so that the pile

pile in the single pile load tests. Strain gauges were

had close-ended condition. Physical and mechanicalparticles as similar to the model single pile.

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

properties of the model piles are listed in Table 2.

25

50

25

20
Head cap
SG level 1

30

50

100

20

glued
sand
particle40
SG level 2

100 mm
30

40

TP4285 mmSG level 3
40
SG level 4

255

TP3

40

TP2

SG level 540

TP1

SG level 635close-ended

Fig. 85End cap

Configurations of the 4-pile pile foundation

Axial strain gauge
Shear strain gauge

Fig. 7285 mmTable 3.

Configurations of the model piles consisted in the 4-pile

cap used in the 4-pile pile foundation

pile foundation
Table 2.

Physical and mechanical properties of the model piles

consisted in the 4-pile pile foundation

Type of material
Pile length, L (mm)Physical and mechanical properties of the model pile

Aluminium alloy
JIS A6063
285

Type of material

Aluminium alloy

Width, B (mm)100

Length, L (mm)100

Thickness, t (mm)30Pile spacing, s (mm)50

Normalised pile spacing, s/D

2.5

Density,  (g/cm )

2.79

3

Outer diameter, Do (mm)20Young's modulus, E (MPa)73,000Inner diameter, Di (mm)17.8

Poisson's ratio,

0.33

Wall thickness, t (mm)1.1

Density,  (g/cm )2.70

Young's modulus, E (MPa)65,000

Soil particle density, ρs (g/cm3)

2.668

0.33

Minimum dry density, ρdmin (g/cm3)

1.269

Maximum dry density, ρdmax (g/cm3)

1.604

Fig. 8 shows the configurations and dimensions ofMaximum void ratio, emax

1.103

the 4-pile pile foundation. The pile cap or raft was madeMinimum void ratio, emin

0.663

of aluminium alloy JIS A2017 that had physical andCohesion, c' (kPa)0mechanical properties as listed in Table 3.

Internal friction angle, ' (degree)

42.8

Poisson’s ratio, 

0.30

3

Poisson's ratio, 

Table 4.

2.2. Model groundThe sand that has physical and mechanical properties

Properties of the sand used as model ground

Model ground density,  (g/cm )1.524

Model ground relative density, Dr (%)

80

3listed in Table 4 was used as the model ground throughout
the experiments. The model single pile and the model 4pile pile foundation were set in the model ground of dry

2.3. Model sheet pile walls (SPW)A PVC (polyvinyl chloride) pipe of 140 mm in innersand which was prepared in a cylindrical model ground

diameter and 135 mm in length as shown in Fig. 10 was

container as shown in Fig. 9.

employed as the model SPW1 in the reinforcement stageof 4-pile pile foundation load tests. Strain gauges were

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

instrumented on the outer surface of SPW1 to measure

Table 5.

vertical (axial) and horizontal (hoop) strains during load

Type of material

PVC

tests. Geometrical and mechanical properties of the model

Outer diameter, Do (mm)151

SPW1 are listed in Table 5.

Inner diameter, Di (mm)140

Height, H (mm)135model groundof dry sand

Properties of the model SPW1

Wall thickness, t (mm)5.5

Density,  (g/cm )1.415

Young's modulus, E (MPa)2,100Poisson's ratio, 

0.31

3

566 mm

The model SPW2 made of PVC pipe of 131 mm in
inner diameter and 250 mm in length as shown in Fig. 11
was employed in the reinforcement stage of the single pile

580 mmload tests. The outer surface was instrumented with strain
gauges similar to the model SPW1. Geometrical andmechanical properties of the model SPW2 are listed inTable 6.
Fig. 9Configurations of the cylindrical model groundcontainer

model
SPW2
(PVC)

strain
gauge

model
SPW1
(PVC)

strain
gauge

131
25
LV-T
LH-T

RV-T
RH-T

LV-M
LH-M

RV-M
RH-M

LV-B
LH-B

RV-B
RH-B

140
LV-T
LH-T

RV-T
RH-T

LV-M
LH-M

RV-M
RH-M

LV-B
LH-B

RV-B
RH-B

100

250 mm

17.5

135 mmDo = 140 mm
Di = 131 mm

50

100

50

250 mm
25

140

SPW2

17.5
151

Fig. 11

Configurations of the model SPW2

Table 6.

Do = 151 mm
Di = 140 mm

Properties of the model SPW2Type of material

PVC

Outer diameter, Do (mm)140

Inner diameter, Di (mm)131

Height, H (mm)250

Wall thickness, t (mm)4.5

Density,  (g/cm )1.415

Young's modulus, E (MPa)1,900Poisson's ratio, 

0.20

3

135 mmSPW1
Fig. 10

Configurations of the model SPW1

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

In the reinforcement stage, the inside of SPW2 was

3. Experimental results
3.1. Vertical load tests on the single pile
In series of vertical load tests (VLTs) on the single pile,refilled with the sand in 3 steps (No. 6 to No. 8) as shown

VLTs in the initial stage, the embedment reduction stage

was recovered to that in the initial condition of 400 mm.

(simulating

riverbed

soil

excavation)

andin Fig. 13. In the step No. 8, the pile embedment lengththereinforcement stage were carried out in the same model
load cellground. The model pile was a kind of bored pile. First, thedial gauges

model ground of 180 mm in height was prepared, secondly
the model pile was set on the model ground, and then themodelsingle pilesand was poured around the model pile until the totalheight of the model ground reached 580 mm. In theembedment reduction stage, the top 50 mm ground wasstrainamplifiers

removed 4 times as shown in Fig. 12 (steps No. 2 to No.
5). At step No. 5, the embedment length, Ld, was reduced

model
SPW2

to 200 mm from the initial embedment length of 400 mm.
After the load test at step No.5, SPW2 (Fig. 11) was set onVthe ground surface.
model
SPW2

motor
jack rodload cella single
pile model
filled
sand

200

8
80
7
6

model
single pile

50
70

5

580

200

200

strainamplifiersmodel ground(dry sand, Dr = 80%)cylindrical model
ground container

566 mmVa single
pile modelFig. 13

Test conditions and sequences of VLTs on the single

pile in the reinforcement stage
200

1 initial G.L.
2
3
4
5

Fig. 14 shows load-settlement curves in the initial
50
50
50
50

580

stage No. 1 and in the embedment reduction steps No. 2 to200

No. 5. It is seen that vertical resistances of the piledecreased with the reductions of pile embedment lengthfrom No. 1 to No. 5. Furthermore, though the pile200

embedment was remaining 50% in the final embedment
reduction step No. 5, the yield resistance of about 900 N
model ground(dry sand, Dr = 80%)

was less than 50% of the yield resistance exceeding 2,100
N in the initial stage No. 1.

566 mmFig. 12Fig. 15 shows load-settlement curves in the final

Test conditions and sequences of VLTs on the single

pile in the initial stage and the embedment reduction stage

embedment reduction step No. 5 and in the reinforcement
steps No. 6 to No. 8 comparing with the result in the initialstage No. 1.

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

Axial force, Fa (N)Vertical load on pile head, V (N)
500

1,000

1,500

2,000

0

2,500

D = 32 mm

1
2

5

4

3

2

1

3
4
5

VLTs on a single pile (reduced stage)

6

1 Initial
Ld = 400 mm
2 Reduced Ld = 350 mm
3 Reduced Ld = 300 mm

Fig. 14500

4 Reduced Ld = 250 mm
5 Reduced Ld = 200 mm

Initialstage #1
D = 32 mm
Ld= 400 mm

100

200

Initial G.L.= 200

300

w/D = 0.01
w/D = 0.02
w/D = 0.05
w/D = 0.10
w/D = 0.14

400

500

600

(a) in the initial stage No.1

Load-settlement curves of VLTs on the single pile in

the initial stage and the embedment reduction stage

Axial force, Fa (N)0Distance from pile head, z (mm)pile increased from No. 5 to No. 8 with increasing pileembedment length using the SPW reinforcement. At the
final reinforcement step No. 8, the yield resistance of thepile recovered to about 70% of that in the initial stage No.
1 (or to about 140% of that in the final embedment
reduction step No. 5).
Vertical load on pile head,V (N)
1,000

1,500

0

2,000

2,500

100

200

300
Reduced G.L.= 400

400

w/D = 0.01
w/D = 0.02
w/D = 0.05
w/D = 0.10

500

600

1
2

Initial

3

5

7

8

(b) in the final embedment reduction step No.5

1
Axial force, Fa (N)

4
0

5
6

500

1,000 1,500 2,000 2,500

0

VLTs on a single pile (reinforced stage)

5 Reduced Ld = 200 mm
6 Reinforced Ld = 270 mm

Fig. 15

1,000 1,500 2,000 2,500

Reducedstage #5
D = 32 mm
Ld= 200 mm

D = 32 mm

7 Reinforced Ld = 320 mm
8 Reinforced Ld = 400 mm

Load-settlement curves of VLTs on the single pile in

the reinforcement stage

Fig. 16 shows the axial force distributions of the pile(a) in the initial stage No.1, (b) in the final embedment
reduction step No.5 and (c) in the final reinforcement stepDistance from pile head, z (mm)Pile head settlement (mm)

500

500

0

It is seen from Fig. 15 that vertical resistance of the0

1,000 1,500 2,000 2,5000Distance from pile head, z (mm)Pile head settlement (mm)00No. 8. It is seen from the comparison of Fig. 16 (a) and100

Reinforced
stage #8
D = 32 mm
Ld= 400 mm

200

Inside SPW
Fill = 200

300

400

500

(b) that not only shaft friction resistance but also pile tip(c) in the final reinforcement step No. 8

decreased compared with those of the initial stage No.1
Fig. 16- 105 -

w/D = 0.01
w/D = 0.02
w/D = 0.05
w/D = 0.10
w/D = 0.15

600

resistance in the final embedment reduction step No. 5
due to the influence of pile embedment length reduction.

Outside SPW
G.L.= 400

Axial force distributions of the single pile in VLTs

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

In the final reinforcement step No. 8 (Fig. 16(c)), thevertical resistance of the pile was improved due to theload cellmortorjacking rod

recovery of pile embedment length using the SPW

dial gauge

reinforcement. However, the pile resistance in the final
reinforcement step No. 8 was not fully recovered

dial gauge
reducedgroundlevel

comparing with the results of the initial stage No.1 (Fig.
16(a)).
3.2. Vertical load tests on 4-pile pile foundation
In Sections 3.1, effectiveness of themodel SPW
(PVC pipe)

4-pile pilefoundation

SPW

reinforcement was demonstrated. In order to investigate
the effectiveness of the SPW reinforcement more in detail,filled
sand
model
SPW1

vertical load tests on the 4-pile pile foundation model werecarried out.
Similar to the VLTs on the single pile, VLTs on the 4-

V

15
7
6

pile pile foundation were carried out in the initial5

4

condition and in each stage of the pile embedment length

4-pile pilefoundation
15
60
60

120
120

reduction and the SPW reinforcement, as shown in Fig. 17580(reduction stage) and Fig. 18 (reinforcement stage).

model ground(dry sand, Dr = 80%)

mortorjacking rod
load cell

566 mmFig. 18
dial gauge

dial gauge

Test conditions of VLTs on 4-pile pile foundation in

the reinforcement stage

In the reinforcement stage, SPW1 was located very
4-pile pilefoundation

dry sandmodel groun dclose to the model foundation, as shown in Fig. 19. It is
desirable to minimize the size of the SPW so that the SPW
structure does not interfere the river stream as much asV
1 initial G.L.

4-pile pilefoundation
2

15
3 60
4 60

possible when the SPW reinforcement is applied to an
actual bridge foundation.

15

100
120

(in mm)
model
SPW1

120
580

100

model ground(dry sand, Dr = 80%)model
4-pile pilefoundation
140

566 mmFig. 17

Test conditions of VLTs on 4-pile pile foundation in

the initial stage and the embedment reduction stage

Fig. 19

Top view dimensions of SPW reinforcement in VLTs

on 4-pile pile foundation- 106 -

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

Fig. 20 shows load-settlement curves in the initialhoop strains and axial strains of the SPW with increasingstage No.1 and the embedment reduction steps from No. 2

normalised settlement of the foundation, w/D, where w is

to No. 4. It is seen that vertical resistances and initial

the settlement and D is the pile diameter, respectively,

stiffness of the pile foundation decreased with theduring load test in the final reinforcement step No. 7. Note

reductions of pile embedment length from No. 2 to No. 4.

that compression strain is taken as positive and tension

It is also seen that the load-settlement curves in thestrain is taken as negative. It is seen that the maximum

reduction steps No. 2 and No. 3 exhibit a plunging

values of both hoop strain and axial strain were generated

behaviour and the response in step No. 4 exhibits aaround the SPW base.

softening behaviour, while the response in the initial stage

Vertical load, V (N)No. 1 shows a progressive failure behaviour.
Average settlement, w (mm)0

It is interesting to notice that the load-settlement
behaviour in the stage No. 1 is different from those in theother stages. The initial stiffness of the load-settlement
curve at the stage No. 1 is much higher than those in theother stage, and the pile at the stage No. 1 has higher
resistance at larger settlements.
A reason for these results is attributed to the existenceof the raft resistance in the stage No. 1. A part of thethe soil. Although the figure is not shown, the shaft
resistance of the piles in the stage No. 1 was larger than

4,000

5,000

6,000

D = 20 mm

14 (PG)

2
3

3
(PG)

4
5

1 (PR)
2(PG)

6

VLTs on 4-pile foundation (reduced stage)

7

3 Reduced Ld = 180 mm
4 Reduced Ld = 120 mm

Fig. 20
Load-settlement curves of VLTs on 4-pile pilefoundation in the initial stage and the stage of pile embedment
reduction
Vertical load, V (N)stiffness of the load-settlement curve at the stage No. 1. At
Average settlement, w (mm)0larger settlements, the raft resistance was mobilised larger,
resulting in the larger total vertical resistance of thefoundation in the stage No. 1.
It is also noted that the tangent stiffness at the stage
No. 1 when w was around 0.5 mm was smaller than thosein the other steps (No. 2 to 4). A reason may be thedifference in the base stiffness of the pile. The basestiffness would have been lower at the stage No. 1 because

1,000

2,000

3,000

4,000

5,000

6,000

0

D = 20 mm

1
2

4 (PG)

6 (PG)

7 (PR)

3
4
5

5
(PG)

1 (PR)

6
7

VLTs on 4-pile PF (reinforced stage)

4 Reduced Ld = 120 mm
5 Reinforced Ld = 180 mm

the pile was in a bored state in case 1 and was in jacked
previous load test.

3,000

0

those in the other stages. This fact increases the initialstate in No. 2 to 4 due to the penetration of the pile in the

2,000

1 Initial
Ld = 255 mm
2 Reduced Ld = 240 mm

vertical load is transferred to the soil beneath the raft base,resulting in the increase of stress level and the stiffness of

1,000

Fig. 21

6 Reinforced Ld = 240 mm
7 Reinforced Ld = 255 mm

Load-settlement curves of VLTs on 4-pile pilefoundation in the reinforcement stage

Fig. 21 shows load-settlement curves in thereinforcement steps from No.5 to No.7, comparing withthe results in the final embedment reduction step No.4 andthe initial stage No. 1. It is seen that the vertical resistancesand stiffness of the 4-pile pile foundation increased fromstep No. 4 to step No. 7 with increasing pile embedment
length using the SPW reinforcement. In particular, thevertical resistance in the final reinforcement step No. 7
was much greater than that of the initial stage No. 1.

It is also seen that absolute magnitudes of the hoopstrains are larger than those of the axial strains at each w/D.
This means that the soil inside the SPW is subjected tolarge horizontal stresses by the existence of SPW. It isreasonable from the comparison of Figs. 20 and 21 that thefoundation at step No. 7 has the resistance larger than thatof the initial stage due to the contact of the raft on the
ground.

Figs. 22 and 23 show changes of distributions of- 107 -

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

Distance from SPW top (mm)-800

SPW hoop strain, h (ST)
-600

-400

0

to the soil inside the SPW. The horizontal stresses as well

-200

0

as vertical stress in the soil are increased by the increase

Inside SPW fill = 0

in the raft base stresses owing to the existence of the SPW.

VLT reinf. No.7
30

Hence, it seems to be reasonable the raft resistancew/D = 0.01
w/D = 0.02
w/D = 0.03
w/D = 0.05
w/D = 0.10
w/D = 0.15
w/D = 0.20
w/D = 0.30

60

90

after the construction of the SPW becomes larger than thatin the initial condition. It is inferred from the experimental
results that efficiency of the SPW reinforcement isgoverned by size relative to the existing foundation andstiffness of the SPW as well as stiffness of the soil inside
the SPW.

120
Outside SPW G.L.= 135

Fig. 22

SPW base = 135

SPW hoop strain distributions in the final

4. Concluding remarks
From the experimental results of model load tests on

reinforcement stage of VLTs on 4-pile pile foundation

single pile and 4-pile pile foundation, it was demonstrated
SPW axial strain, a (ST)

Distance from SPW top (mm)

0
0

200

400

600

that the method of SPW reinforcement is very efficient and800

promising. On the other hand, numerical analyses of some

Inside SPW fill = 0

actual pile foundations which have potential risks of

VLT reinf. No.7
30

settlement and collapse in Thailand should be carried out

w/D = 0.01
w/D = 0.02
w/D = 0.03
w/D = 0.05
w/D = 0.10
w/D = 0.15
w/D = 0.20
w/D = 0.30

60

90

to find efficient configurations of the sheet pile wall
reinforcement. Finally, in order to investigate theinfluences of flood load and scouring, and to validate theproposed reinforcing method, a full scale field test should
be carried out.

120
SPW base = 135

Fig. 23

The reinforcement mechanism of the SPW method

Outside SPW G.L.= 135

mentioned above was confirmed through numerical

SPW axial strain distributions in the final

analyses of the experiments by Tikanta et al (2017).

reinforcement stage of VLTs on 4-pile pile foundation

References

V
Virtualraft

Fukada, H., Kato, K., Aoyagi, M., Inagawa, H and Shioi,
Y. 2005. Application of Reinforcing Methods for

SPW

Existing Pile Foundation on Soft Ground (In-cap
Method). Public Works Research Institute: The 23rd
US - Japan Bridge Engineering Workshop.
Retrieved July 1, 2014(www.pwri.go.jp/eng/ujnr/tc/g/pdf/23/23-73kato.pdf)
Tikanta, T., Matsumoto, T., Vu, A.T., Kobayashi, S.,
Shimono,Fig. 24

Conceptual expression of stress transfer from the raftto the soil inside the SPW

S.

and

Bamrungwong,

C.

2017.

Fundamental experiments on a reinforcement
method using sheet pile wall for bridge pilefoundations subjected to pile embedment reduction

Fig. 24 shows a conceptual expression of stressand numerical validation, Geotechnical Engineeringtransfer from the raft base to the soil inside the SPW. A

Journal of the SEAGS & AGSSEA, Vol. 48, No. 3,part of the vertical load on the foundation is supported by

pp. 26-39.

the raft. The vertical stresses at the raft base are transferred- 108 -