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

An Investigation of Effect of Distance and Shape of Pile on the Displacement ofGag Pile by 3D FEM Analysis
Kohei NAGAI
Associate Professor, Institute of Industrial Science, The University of Tokyo, Japan
Email: nagai325@iis.u-tokyo.ac.jp

Naoki SUZUKI
Construction Solutions Department, GIKEN LTD., Japan

Yukihiro ISHIHARAManager, Press-in Technologies Support Department, GIKEN LTD., Japan

Taro UCHIMURA
Associate Professor, Graduate School of Science and Engineering, Saitama University, Japan

ABSTRACT
Press-in 3D FEM analyses were carried out to examine the behavior of a buried gas pipe and the soil ground during thepress-in installation of a sheet pile. The displacement of a buried gas pipe was set as the parameter to investigate thegas pipe behavior. In the first analytical model, both of the sheet pile and the gas pipe were modeled as rectangularsolid structures and the horizontal distances between a sheet pile and a buried gas pipe were arranged in 100mm,200mm, 500mm and 1000mm. In the second model, not only the rectangular shape but also a standardized shape(SP-3) based on the real model was made as a sheet pile. In addition, 6 series of modeling were prepared in terms of thesetting direction of the SP-3 sheet pile and the horizontal direction between the sheet pile and the gas pipe. In order toclarify the behavior of the inside ground, strain contour diagrams were shown in addition to the displacement of the gas
pipe. Through these two types of analyses, the effect of the press-in installation to underground structures wasdiscussed.
Key words: press-in method, SP-3 sheet pile, displacement of gas pipe, 3D FEM analysis

1. Backgroundvertical deflections of a gas pipe under the different

1.1. PlaceThe Press-in method enables construction in narrowhorizontal distances between the steel sheet pile and thespace and it is widely used in urban areas, so the number

piles were pressed into the ground up to 1.5m in depth. Fig.

of neighboring constructions is increasing. Threfore, it

1 shows the layout of this experiment. Press-in

becomes important to understand the behavior during theconstruction was done from the left to the right side of Fig.

press-in execution and evaluate the influence on the1. The gas pipe made of polyethylene was laid

existing structures in the ground to avoid the damage ofunderground 1.0m in depth from the ground level inthem.

advance and its both ends were fixed not to movegas pipe from 100mm to 1106mm when the steel sheet

A field experiment with a gas pipe has beenhorizontally except for the rotation (Fig. 2). Through thisconducted for the purpose of showing some conditions

experiment, the maximum deflection was about 7mm andquantitatively which preserve the soundness of existing

the maximum external force applied to the circumferentialstructures (Yamakawa, 2014; Giken et al., 2014). The

direction was about 50kPa when the horizontal distancemain subjects of this measurement were the horizontal andbetween the steel sheet pile and the gas pipe was 100mm.

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Fig. 1

Experimental layout (unit: mm)

the breaking external force is around 200kPa. Here, thesafety factor against the circumferential deformation isabout more than 4. As a result of this experiment, the gas
pipe is not damaged when the horizontal distance between
the steel sheet pile and the gas pipe is more than 100mm(in cases of pressing-in individually) or 200mm (in casesof pressing-in with auger).
Though this experiment shows some clear numbers
and evaluation, the general applicability is not enoughbecause of its specific experimental qualifications. ToFig. 2

understand the behavior in the ground more clearly,

State of gas pipes and press-in construction

numerical simulation becomes a useful approach. In thisstudy, therefore, the underground gas pipe displacement
was set as the main subject to measure when the pile waspressed-in beside it. Then, the relationship between thegas pipe displacement and the horizontal distance between
the steel sheet pile and the gas pipe, and the soil behavior
under pressing-in several different types of steel sheet
piles was investigated by using 3D FEM analysis(Maekawa et al., 2003). Even though this study is basedon the above field experiment, the aim is not to follow theexperimental result on the analysis but to get qualitative
tendency of the behaviors.
2. Effect to the horizontal distance between steel sheetpile and gas pile2.1. Analysis modelFig. 3 shows the analysis model from the view of X
Fig. 3axis. Each of the three materials, soil, gas pipe and sheet

Analysis model

pile, was modeled as a rectangular solid and both soil andIf the concentrated load is applied to the center of this gas
pipe, the breaking deflection is around 440mm. In thisviewpoint the safety factor against deflection is aboutgas pipe were modeled as elastic bodies, elastic 1 andelastic 3 (Table 1). Size of the each model is as follows;

more than 60. Moreover, if the uniform distribution
external force is applied to the circumferential direction,- 430 -Soil: (x,y,x)=(3000,4000,2000mm),
Gas Pipe: (x,y,z)=(2400,100,100mm),

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

Sheet Pile: (x,y,z)=(600,200,1000mm).
The bottom and side surfaces of the soil groundwere fixed in every directions. The gas pipe was placedin the soil. 100mm displacement in the minus Z direction
was given in 10 steps to the sheet pile which was alreadylaid underground by 500mm in depth. Interfaces betweenthe pile and soil emements are fixed and move together
for the simplicity. The papameter of the analyses are thehorizontal distances between the sheet pile and the centerof gas pipe that are 100, 200, 500, and 1000 mm.
2.2. Results of analyses

Fig. 4

Fig. 4 shows the maximum horizontal and vertical

Relationship between horizontal distance and pipe
displacement

displacement of the gas pipe when the horizontal
distance between the sheet pile and the gas pipe waschanged from 100, 200, 500, and to 1000mm. The
horizontal displacement increased from 100mm to500mm in horizontal distance and the maximum
horizontal displacement was about 6mm in 500mm. On
the other hand, the vertical displacement showed that it
became inversely proportional consistently from 100mm
to 1000mm in the horizontal distance. In other words, thecloser the distance between the sheet pile and the gas
pipe was, the more the gas pipe was affected by the sheet
pile in vertical direction. Fig. 5 shows the relation
between the horizontal and the vertical displacement ofFig. 5

the gas pipe. If each point is connected to the origin, each

Relation between horizontal and vertical pipe
displacement

line shows the displacement vector of the gas pipe. Thebigger the distance between the sheet pile and the gas
pipe was, the smaller both the slope and the length of theNo.2 sheet piles were modeled as a rectangular solid,

displacement vector were.

thickness t=13mm, length in the X axis direction
L=300mm or 400mm, and the horizontal distance to the

3. Effect of the shape of sheet pilesurface of the gas pipe d=200mm. The other No.3-No.6

3.1. Analysis model
In order to examine the influence of the shape andsheet piles were modeled as steel sheet pile SP-3 shapes

the positional relation of the sheet pile, 6 types ofThe height of the sheet pile in the Z axis direction wasanalyses were carried out (Fig. 6). In Fig. 6, No.1 and1000mm and its 500mm was already laid underground atused at the actual site, L=400mm, t=13mm, h=125mm.

first. Given the displacement of the sheet pile wasTable 1.

Material properties for analysis

100mm in the minus Z axis direction and the press-in

Material

Young’s modulus

steps were 10. The size and restriction condition of theSoil (elastic 1)7.27 MPa

soil and pipe solid were the same as the second chapter,

Soil (elastic 2)

7.27 MPabut the material properties of the soil and the gas pipe

Gas pile (elastic 3)0.73 MPa

were changed to elastic 2 and elastic 4 to make theGas pile (elastic 4)

750 MPa

models close to the actual things (Table 1).

Sheet pile (steel)

206 GPa- 431 -

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

Y- horizontal pipe displacement (cm)Z-vertical pipe
displacement (cm)

0 0.1 0.2 0.3 0.4 0.5
0-0.5
-1

No.1-1.5

No.2-2-2.5(a)Y- horizontal pipe displacement (cm)Fig. 6

Z-vertical pipe
displacement (cm)

0 0.1 0.2 0.3 0.4 0.5

Series of sheet pile modeling3.2. Results and comparison

0-0.5
-1

No.2

-1.5

No.3-2

No.4-2.5(b)3.2.1. Rectangular shape and its length difference
Fig. 7(a) shows the comparison of the gas pipe

Y- horizontal pipe displacement (cm)displacement between No.1 and No.2 models. If the0400mm, both of the horizontal and vertical displacement
became larger by 13% of No.1 displacement and theslope from the origin to two points corresponded to eachother.
3.2.2. SP-3 shape and its direction difference
The difference of sheet pile shape between therectangular (No.2) and SP-3 (No.3,4) is shown in Fig.
7(b). In terms of the comparison between No.2 and No.3,
the displacement of gas pipe of No.3 was bigger by 25%
horizontal

displacement

and8%

in0-0.5-1

comparison between No.2 and No.4, although thehorizontal displacement decreased by 5%, the verticaldisplacement increased by 15% in No.4 compared to thatof No.2. Fig. 8 is a strain contour diagram of the YZ plane
cut through the center of the sheet pile. Strains spread out

No.3

-1.5
-2

No.5

-2.5
(c)

0 0.1 0.2 0.3 0.4 0.5

verticaldisplacement than that of No.2. In regards to the0.1 0.2 0.3 0.4 0.5

Y- horizontal pipe displacement (cm)Z- vertical pipe
displacement (cm)inZ-vertical pipe displacement(cm)

length of the sheet pile was bigger from 300mm to0-0.5-1

No.3-1.5-2-2.5(d)on both sides of the sheet pile in No.2 model (Fig. 8(a)),

No.6

however, strain spread mainly to the gas pipe side in No.3
model (Fig. 8(b)) or to the opposite side from the gas pipein No.4 model (Fig. 8(c)). That is why the horizontal
displacement of No.4 became smaller than that of No.2.

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Relation between horizontal and vertical pipe
displacement

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi(a) No.2 model(a) No.3 model(b) No.6 modelFig. 9(b) No.3 model

Strain contour diagram just under the bottom of sheet
pile

3.2.3. Influence of the minimum horizontal distanceand an existing sheet pile
The comparison between No.3 and No.5 according
to the horizontal distance is shown in Fig. 7(c). The
results of No.5 was quite similar to the results of No.4.
One possible reason is the similarity of the minimum
horizontal distance between the sheet pile and the gaspipe.
Fig. 7(d) also shows that the results of No.6 wasroughly the same with the results of No.4 and No.5. In(c) No.4 modelFig. 8

No.6 model, the left sheet pile whose height was more

Strain contour disgram

than 1.5m had been laid underground 1.5m in depth

It is possible to say that the wing parts of SP-3 sheet pile
contribute to generating the horizontal displacement ofgas pipe in No.3 or the vertical displacement of gas pipe in
No.4 when the minimum horizontal distance between thewing parts and the gas pipe is taken into account.

before pressing-in the right sheet pile. Fig. 9 are strain
contour diagrams of the XY plane cut just under thebottom of the sheet pile after pressing-in. The way of thespread of soil strain of No.6 (Fig. 9(b)) was different
from that of No.3 (Fig. 9(a)) due to the exsisting sheet
pile.

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4. Conclusions
The gas pipe displacement was measured when thesteel sheet pile was pressed-in by 100mm from 500mm
to 600mm in depth beside the gas pipe laid underground1.0m in the depth by using 3D FEM analysis. In the firstanalysis that the horizontal distance between the sheet
pile and the gas pipe was changed from 100mm, 200mm,
500mm and to1000mm, the smaller the horizontal
distance was, the bigger the pipe displacement became.
Besides, the horizontal pipe displacement reached themaximum value at the 500mm in horizontal distance. In
the second analysis that the shape of the sheet pile and its
direction were changed in several cases, the SP-3 shapesheet pile made the pipe displacement bigger than therectangular shape in any case. Moreover, the lateral partof SP-3 shape produced strain spreads of soil groundtoward the opposite side from the wing parts. So, in thecase of SP-3 shape, the way of propagation of strain in
soil ground was different from that of the rectangularshape.
References
Yamakawa, T. 2014. Influence of the Press-in Method onburied pipes, Bachelor's Thesis, The University ofTokyo, 202p. (in Japanese)
Giken, Uchimura, T., Nagai, K. 2014. Field test resultson the influence of the installation of sheet piles bystandard press-in and press-in with augering on theexisting gas pipes, Technical Material, Giken, 16p.
(in Japanese)
Maekawa, K., Pimanmas, A. and Okamura, H. 2003.
Nonlinear Mechanics of Reinforced Concrete, CRC
Press.

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