8th Int. Conf. on Geotechnique, Construction Materials and Environment,
Kuala Lumpur, Malaysia, Nov. 20-22, 2018, ISBN: 978-4-909106001 C3051

NUMERICAL ANALYSIS FOR 3D INFLUENCE OF
PILE PULLING-OUT HOLES ON SURROUNDING GROUND
Shuichi Kuwahara 1 and Shinya Inazumi 2
1Marushin Co. Ltd., Japan
2Shibaura Institute of Technology, Japan

ABSTRACTThe demolition of social infrastructures including the civil structures have been increasing because of aging
them constructed during in a period of high economic growth and decrease in their utilization with a population
decrease, in recent years. As a result, removal works of existing pile in the ground have been increasing. Pullingout method is adopted for removal of existing a pile foundation in the present circumstances. However, after
pulling-out a pipe foundation, decline of mechanical characteristic of surrounding ground is concerned byforming pulling-out holes. There are no regulations yet for filler injected into a pulling hole, and the influence ofthe strength of the filler on surrounding ground is not considered. This study considers the influence by which apulling-out hole of a pipe foundation gives it to static characteristics of surrounding ground by using 3D elasticplastic finite element analysis. The special qualities required for fillers injected into a pulling-out hole are also
clarified in this study.
Keywords: Finite element method, Pile foundation, Pulling-out method, Pulling-out hole,and cement-bentonite use has increased. However,there are no regulations yet on fillers injected into apulling-out hole, and the influence by which thestrength of the fillers gives it to the surroundinggrounds is not also elucidated.
This study considers the influence by which apulling-out hole of a pile foundation gives it to static
characteristics of surrounding grounds by using
three-dimensional static finite element analysis. The
special qualities required for fillers injected into apulling-out hole are also clarified in this study.

INTRODUCTION
In Japan, many of the city located in the soft
ground, there are many structures using a pilefoundation. Therefore, to achieve a new land
utilization at the place where existed structures arepresent, it is necessary to remove existed pile
supported the structure as well as existed structures
for construction of a new structure. Further, existedpiles and concrete husk become industrial waste, beleft of these industrial waste in the ground is a very
difficult problem. In addition, it is seen troubles
many as "hidden defect" in the sale of landtransactions [1]. Accordingly, it can be said that theremoval of existed pile is essential.
The removal method of existed pile, there is apulling-out method and crushing removal method,
and the like. But the crushing removal method arehaving such as vibration, noise and environmental
problems. The pull-out method has been widely usedfrom this thing. However, there are also problems in
the pull-out method. The pulling-out hole is formed
when pulling out the existed pile. If the pulling-out
hole is left, the collapse of the empty drilling part ofthe earth and sand, and there is a possibility that thesubsidence of the ground surface by the gap
widening in the ground occurs. Therefore, it isnecessary to fill the pulling-out hole by injection of
the fillers. About fillers, conventionally, in manycases to construction in mountain sand and recycled
sand from construction it is easy and inexpensive.
But, by cannot ensure a reliable filling and stablestrength, in recent years the flow of processing soil

STUDY SUMMARY ABOUT THE STATICBEHAVIOR OF THE PULLING-OUT HOLE
AND THE ORIGINAL GROUND

Fig. 1 Analysis procedure105

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Table 1 Element parameters
Material nameClay layer

Gravellayer

filler𝜸𝒕(kN/m3)

1419

15

Constitutive
law

Elastic-plastic model

Table 2 Ground parameters
Material nameClay layer

Gravel layer

𝑬(kN/m²)

7900

140000

𝝂(-)

0.45

0.35

𝑺𝒖 (kN/m³)

37.8

152.9

𝝓 (°)

042.3

(a) When the pulling-out holes are hollow

Table 3 Filler parameters(b) When the pulling-out holes are injected the filler

Fillerqu(N/mm²)

1

0.1

2

0.5

3

1.0

𝑬
(kN/m²)
1.36×10⁵
5.88
×10⁵
11.5×10⁵𝝂
(-)

𝑺𝒖(kN/m³)

𝝓(°)

0.48

38.3

26.0

0.48

182.3

39.5

0.48

362.2

49.6

In the analysis, the analysis cross-section has atwo-layer, upper layer part is clay layer as soft strata,
which N value is about 2. And under layer part isgravel layer as strong formations serving as asupport layer, which N value is about 50. The frontand side width of the analysis cross section is set to50m, the thickness of the clay layer is 18m, thethickness of the gravel layer is 8m, and the total
depth of the cross section is 26m. About pulling-out
holes, the number is three, pore diameter is 2m,
depth is 20m, and embedment depth into the gravel
layer is the 2m. For mesh division, improve theaccuracy of analysis by finer mesh spacing near thepulling-out hole. Also, even when filled withpulling-out holes, it is finer mesh in order toexamine the behavior of the filling portion of thepulling-out hole. As a boundary condition, thebottom is fixed fulcrum, and the lateral boundary isfixed in the vertical direction.
In the analysis, filler material is fluidization
treated soil [2], [3]. The analysis cross-sectionalview of the ground, analysis model and axial
direction are shown in Fig. 2. In the figure, theportion surrounded by red frame is hollow portionand blue frame is filler portion. And a yellow line
indicates a boundary between clay layer and gravel

Fig. 2 Sectional view and Analysis model

Describe the content of this study with (1) to (4)(see Fig. 1).
(1) To select the study cross-section.
(2) To create the analysis model, based on theselected cross-section in the 1. And the analysis
area to mesh division.
(3) To select an analysis constant. To set theapplication configuration model and material
parameters in the initial stress analysis.
(4) Perform the initial stress analysis. Analysis
technique is a total stress analysis. In this study,
elastic-plastic model for the ground material andhollow portion has been applied.
THE STATIC BEHAVIOR OF THE PULLINGOUT HOLE AND THE ORIGINAL GROUND,ANALYSIS MODELAnalysis Model106

GEOMATE - Kuala Lumpur, Malaysia, Nov. 20-22, 2018(a) Pulling-out holes are hollow(b) Filler 1 (qu=0.1N/mm2)(c) Filler 2 (qu=0.5N/mm2)(d) Filler 3 (qu=1.0N/mm2)

Fig. 3 X-direction displacement amount contour figure at ground surface

ratio. Su represents shear strength. ϕ representsinternal friction angle. qu represents compressivestrength.

layer.
Constitutive Law and Material Parameters
Parameters in the clay layer and gravel layer
used for the analysis and soil parameters in thepulling-out hole are shown in Tables 1 and 2. In thisanalysis, using a fluidizing processing soil that manyof the experimental value. In addition, it analyzes inthree fillers with different elastic modulus of thefluidizing process soil in order to examine the effectof filler strength has on the ground. From having asmall strength, the filler 1, filler 2, filler 3.
Parameters used in the analysis is to determine theanamnestic literature reference (see Table 3).
t represents unit volume weight of the soil. Erepresents elastic coefficient. ν represents Poisson's

ANALYSIS RESULTS AND STUDY ON THE
DYNAMIC BEHAVIOR OF THE PULLINGOUT HOLE AND THE ORIGINAL GROUND
In this study, to compare the ground when
injecting three types of filler on the ground when thepulling-out holes are hollow, in the static analysis.
The results are shown in the following.
Results of the Analysis
Figures 3, 4 and 5 show the results about the107

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2(b) Filler 1 (qu=0.1N/mm )(a) Pulling-out holes are hollow

22(c) Filler 2 (qu=0.5N/mm )(d) Filler 3 (qu=1.0N/mm )Fig. 4 Settlement amount contour figure at ground surface

effect of the pulling-out holes in the hollow and 3
types of fillers with different strength on thesurrounding ground by this study. Figure 4 is thecontour figure showing x-direction displacement
amount on the ground surface when the pulling-outholes are hollow and when each filler with differentstrength is fixed. Figure 5 is the contour figure
showing settlement amount on the ground surface inthe same case as above. Figure 6 is the graphcomparing settlement amount on the ground surface
in the same case as above. These are premises thatthe filler is injected uniformly [4].

out holes are hollow. In that case, it shows thatsurrounding ground is deforming to block thepulling-out holes. And the maximum x-direction
displacement amount is 0.001m when the pullingout holes are fixed with filler.
In that case, it shows that surrounding groundon the ground surface is deforming toward the centerof the ground surface. It is because of the filler isresistant to deformation due to the filler is injected.
So that, it can be said that x-direction displacement
is reduced by injecting the filler into the pulling-out
holes. And, x-direction displacement reduces as thestrength of the filler.
From Figs. 4 and 5 the maximum settlement
amount is about 0.30m in the part sandwiched by thepulling-out holes when the pulling-out holes arehollow. It is because that the stress concentrates

Study on the Results of the Analysis
From Fig. 3, the maximum x-direction
displacement amount is 0.080m when the pulling108

GEOMATE - Kuala Lumpur, Malaysia, Nov. 20-22, 2018(b) Filler 1 (qu=0.1N/mm2)(a) Pulling-out holes are hollow(c) Filler 2 (qu=0.5N/mm2)(d) Filler 3 (qu=1.0N/mm2)

Fig. 5 Settlement amount graph at ground surface

around the pulling-out holes by excavation. The areaof influence of settlement in x-direction is -15m to15m and the ground surface rise in the outside thatarea. As downward stress acts by initial stressanalysis, downward stress is released by excavation
and upward stress acts, so it can be said to rise awayfrom the area of influence of settlement. As above, it
can be said that ground improvement is necessary
because the settlement amount is large.
And the maximum settlement amount is 0.008m
when the pulling-out holes are fixed with filler 1(qu=0.1N/mm2). The area of influence of settlementin x-direction is -11m to 11m. And the maximum
settlement amount is 0.004m with filler 2(qu=0.5N/mm2). The area of influence of settlementin x-direction is -9.5m to 9.5m. And the maximum
settlement amount is 0.003m with filler 3(qu=1.0N/mm2). The area of influence of settlementin x-direction is -9.5m to 9.5m. In the case of
injecting filler 1, 2 and 3, no settlement occurs

outside that area. When filler is injected, settlement
amount is less than 0.008m, and settlement amountis greatly reduced as compared with when pullingout holes are hollow. It is because that stressconcentration on pulling-out holes can be prevented
by injecting the filler. Therefore, it can be said thatby fil ling the pulling-out holes, the settlement ofground is suppressed. And the area becomes smaller
as the strength of the filler increases.
From Fig. 4, injecting filler 1 (qu=0.1N/mm2),
the settlement amount is locally large in the filler
part. It is because that the compressive stress acts
greatly from the surrounding ground on the filler
part due to the small filler strength. Comparing filler
2 (qu=0.5N/mm2) and filler 3 (qu=1.0N/mm2), thesettlement amount has only 0.001m difference, andthere is almost no difference in the area of influenceof settlement.
The filler of strength 0.5N/mm2 is defined as thesame strength as the ground, which is prescribed in109

GEOMATE - Kuala Lumpur, Malaysia, Nov. 20-22, 2018

the “Public building construction standard
specification (Building work) [5]”, so it is adopted
as standard compound, in recent years. Besides it
there is no reason.
However, from the above, in this study’s analysis
section, it is desirable to inject the filler of strength
0.5N/mm2 to the pulling-out holes of existing piles
in consideration of economics.

the area of influence of settlement. Therefore, it isdesirable to inject the filler of strength 0.5N/mm2 tothe pulling-out holes of existing piles inconsideration of economics.
As this study’s future work is that it is necessary
to examine the influence of this analysis comparedwith this analysis result when changing groundparameters, arrangement number of the pulling-out
holes, compounding materials for filler. And,identify the strength of filler generally required.

CONCLUSIONSIn this study, the influence of the pulling-out
holes on surrounding ground was evaluated by threedimensional static FEM analysis for development ofpulling-out of existing piles.
When the pulling-out holes are hollow, themaximum settlement amount is about 0.30m in thepart sandwiched by the pulling-out holes. But, when
the pulling-out holes are fixed with filler thatstrength over 0.1N/mm2, the settlement amount isless than or equal to 8mm. And the area of influenceof settlement becomes smaller when the filler injects
into the pulling-out holes than when the pulling-out
holes are hollow. Therefore, it becomes clear that
injecting the filler is an effective means to suppress
ground settlement.
In this study’s analysis section, the settlement
amount is locally large in the filler part when thefiller 1 (qu=0.1N/mm2) injects. And, it is possible toprevent local settlement when the filler 2(qu=0.5N/mm2)
and 3(qu=1.0N/mm2)
inject.
Comparing filler 2 (qu=0.5N/mm2) and filler 3(qu=1.0N/mm2), the settlement amount has almost
no difference, and there is almost no difference inREFERENCES[1] Takao M., Leaving the foundation pile,backfilling denied the defects of ground support
force of the part, agent of accountability
violation was also negative case, RETIO, No.82,
pp.166-167, 2011.
[2] Yasushi F., Futa N., Yasushi U., Keisuke T.,
Study on the Young's modulus of the fluidized
processing soil. Summaries of technical papersof annual meeting Architectural Institute ofJapan, pp.591-592, 2014.
[3] Yasushi F., Deformation properties of thebackfill material which has a fluidity and selfhardening, Town Value-up Management report,
No.37, pp.41-44, 2011.
[4] Marushin Co., Ltd., About the pulling out
method of the existing pile, Retrieved April 21,
2018, from http://marushinn.jp/handbook/[5] Ministry of Land, Infrastructure, Transport andTourism, Public Building Construction Standard
Specification (Building Work) 2013 Edition,MLIT, 2016.

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