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Evaluation of EPS embankment behavior during large-scale earthquakes
by full-scale shaking table tests
Tsuyoshi Nishi1, Takeharu Konami2, Tatsuro Kubota3, Hiroyuki Kyokawa4, Junichi Koseki4,
and Kazuya Yasuhara5
1 Construction Project Consultants, Inc., 4-40-11, Takadanobaba, Shinjuku-ku, Tokyo, 169-0075, Japan
2 Okasan Livic Co., Ltd., 1-8-27, Kounan, Minato-ku, Tokyo, 108-0075, Japan
3 Expanded Poly-styrol Construction Method Development Organization , Takadanobaba, Shinjuku-ku, Tokyo, 169-0075, Japan
4 Department of Civil Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
5 Global and Local Environment Co-creation Institute (GLEC), Ibaraki University, 2-1-1, Mito, Ibaraki, 310-8512, JapanABSTRACT
Regarding the Expanded Polystyrol Construction Method (EPS method) using polystyrol foam, rocking
phenomenon of the top-heavy structure at the time of earthquake is concerned, which is caused by its light weight.
The authors conducted a full-scale shaking table tests against a large-scale earthquake with the aim of evaluating theseismic resistance of EPS embankments using a new type of joint metal binder that joins EPS blocks, which wasdeveloped as a countermeasure. The seismic resistance of the EPS embankment was verified by the tests, and asimulation analysis using a finite element method was also conducted for the purpose of making the test results moreversatile. As a result of the analysis, the behavior observed in the test could be simulated appropriately, and theapplicability of the analytical method was confirmed.
Keywords: EPS Embankment; Full scale shaking table test; Dynamic analysis; Resistance against earthquake;
Joint metal

1 INTRODUCTION
Expanded Polystyrol Construction Method using
expanded polystyrol foam (EPS method) is applied,because of its light weight and high workability, in awide range such as widening embankment on steep
slopes or on the soft ground. On the other hand, due tothe top-heavy structure based on its light weight, it ispredicted that, at the time of earthquake, behaviors suchas rocking phenomenon that may cause problems ofearthquake resistance will occur. Therefore, manystudies on seismic resistance have been conducted and
it is shown that this is a construction method with highearthquake resistance. (e.g., Koga et al. 1991; Hotta etal.1992; Nishi et al. 1998)．On the other hand, In Japanin recent years, great earthquakes we have neverthought of, such as 2011 Earthquake off the Pacificcoast of Tohoku that big quakes lasted long and 2016
Kumamoto Earthquake that huge seismic motions acted
continuously, have occurred. Under such circumstances,
further improvement of seismic resistance of EPS
construction method is required.
Under such background, the authors have developed
a new type of joint metal binders that join EPS blocks(Nishi et al. 2018) to improve the stability, andconducted full scale shaking table test using them wasconducted (Nishi et al 2019). As a result, it was
confirmed that sufficient seismic resistance is showneven under the conditions where large scale
earthquakes continue.
In this report, in order to make the test results moreversatile, simulation of tests by dynamic analysis using
the finite element method have been conducted. As theresult, it was confirmed that behavior of the test isappropriately expressed from the analysis results, theeffectiveness of using the analytical method shown inthis paper for the evaluation of seismic resistance ofactual structures has been shown.
2. SHAKING TABLE TEST
2.1 Test Conditions
In the test, subject was the EPS embankment on theback of the pier, and its shape was structural one asshown in Fig. 1. with a vertical wall shape on both left
and right sides. In many cases, EPS embankment isconstructed on the back of the pier for the purpose of
preventing lateral flow by the soft ground, and theshape in the direction perpendicular to the bridge axis isdouble-sided type. As the influence of rocking is
considered to become a big problem about structureSubject ID:

Preference for oral or poster:with such cross-sectional shape, this shape was selected
as the subject of test.
The width of embankment is 5 m, the depth is 3 m,
and the height of EPS block is set to be 3 m (6 stacks),
6 m (12 stacks), 8 m (16 stacks). Similarly to theconstruction works, reinforced concrete deck withthickness of 100 mm was installed at every 3 m heightof EPS. And, considering the pavement, a concrete
deck with thickness of 300 mm was installed on the topof the model.
Fig. 1. shows the approximate cross-sectional shapeof a case with an EPS height of 8 m as an example. Inthe figure, arranged measuring equipment is also shown.
Measurement was made about acceleration anddisplacement around deck position, and a rotational
acceleration of the center of crown. The rotational
acceleration at the center of the crown was measured
with a gyro meter.
The EPS blocks are connected with the joint metalbinders shown in Fig. 2. There are two types of joint
metal binders, new and old. Fig. 2 shows new type ofbinders. New type of joint metal binders has increased
the number of spikes to strengthen the connecting
power to improve seismic resistance．

・ Unit：mm
・ Concrete plate 300 mm thick on
the top represents weight ofpavement, concrete plates 100
mm thick are middle slabs□ accelerometer

Wire type displacementmeter△ Triaxial gyro sensor〇

Floor plan (Top view)

Side view (Case of EPS 8 m High)

Fig. 1. Outline of EPS embankment used for the test.
150mm

compared with old type binders developed in 1995.
The joint metal binders were installed as a standardof 2 pieces per 1 m2, but in the case of height 3 m ofEPS embankment, 1piece per 1 m2 was installed for thecomparison.
The seismic motion used in the test were a white
noise wave, sin wave whose frequency is changed
stepwise from 10 Hz to 1 Hz, and the design seismic
motion (II-I-1) of Specifications for highway bridges
Part 5 shown in Fig. 3.
2.2 Test Results
In the tests, we compared the performance of the new
joint metal binders and old ones in the cases of 3 m and6 m height of EPS embankment. There were no cracks
in the EPS blocks, but there were openings between theEPS blocks. Fig. 4. shows comparison of the amountof opening between the EPS blocks after tests. In thisfigure, the maximum and average values of themeasured values are shown. This figure shows that joint
opening in the case of new joint metal binders issmaller than that in the case of old joint metal binders,and from this fact, it can be said that the new joint
metal binders have better seismic performance.
In the case of 8 m height, hybrid layout was applied
as the rocking measures. Connection between the top
and bottom of EPS blocks was made by the joint metalbinders with both-sided spikes as shown in Fig. 1, andhorizontal connection was made by the joint metalbinders with one-sided spikes. The effect of the saidlayout was confirmed.
In the conventional layout, the joint metal binders
with both-sided spikes were installed between the EPS
blocks as shown in Fig. 5(a), and the joint metal binders
with one-sided spikes were applied only under the deck.
Hybrid layout is defined as follows; joint metalbinders with one-sided spikes are set between theblocks in the horizontal direction as shown in Fig. 5(b)and that with both-sided spikes are set in the middle ofblocks. In the case of 8 m height, effectiveness ofanti-rocking measures by this hybrid layout wasconfirmed.

00-500-1000
0102030time(sec)Fig. 3. Input Acceleration

EPS 6m HighNew type joint
2(2 pieces/m )Specifications for highway bridges
Abs Max Acceleration=765.9gal

500

10EPS 6m HighNew type joint
2(2 pieces/m )1000

20EPS 3m HighOld type joint(2 pieces/m2)

Acceleration(Gal)Fig. 2. Joint Metal Binders

Max. Value
Ave. ValueEPS 3m HighNew type joint(1 piece/m2)

Joint metal binder B(spikes on one side)30

EPS 3m HighNew type joint
2(2 pieces/m )Joint metal binder A(spikes on both sides)

Amount of Joint opening(mm)40150mmFig. 4. Amount of opening between blocks after shaking test
(performance comparison of metal)

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Close-View.Anti-slip steel(a)Traditional placement（□:Joint metal with both claw(b) Hybrid placement■ :Joint metal with one claw）

Fig. 5. Placement conditions of joint metal bindings

Deformed place

Fig. 7. Situation after shaking (hybrid placement in theforeground)breakout of the joint metal bindings has occurred, andthe block itself moved without restraint. That is to say,the motion shown in above Fig. 6 has occurred.
The seismic motion used in the test is a large-scale
earthquake of 1995 Hyogo-ken Nanbu earthquake
whose frequency in the observation record is corrected.
Fig. 7 shows that there is some deviation in the EPS
embankment with the conventional layout, but no major
deformation has occurred. Thus, earthquake resistanceof the EPS embankment was confirmed.
Fig. 6. Pattern diagram of deformation behavior due to locking

When a large seismic force acts on the EPS
embankment, due to the vertical movement caused byrocking, EPS block is lifted up. As Fig. 6 upper shows,under the conditions of conventional layout, this caused
lifting up of the joint metal binders installed between
the blocks, and connection between the lower
horizontal blocks comes off. Therefore, as shown in Fig.
6 below, by using the joint metal binders with
one-sided spikes for connecting the horizontal blocks,
slipping out due to rocking can be prevented, andconnection between the horizontal blocks can bemaintained.
Fig. 7. shows the situation after the vibration iscompleted. The front side is a hybrid layout and theback side is a conventional layout. Since the slip
deformation of the EPS block on the decks installed
every 3 m was confirmed at the time of vibration, aslip-prevention steel plate was installed on the side ofdecks under the condition of hybrid layout.
In Fig. 7, in the conventional layout on the back side,
the deviation between blocks is confirmed, but on thefront side, almost no deformation is seen. Fig. 7 shows
the situation of large deformation (block breakout) after
the test under the condition of the conventional layout.
There is not a great damage to the joint metal binders
themselves, and EPS block leaves some claw marks but
no major damage has occurred. This shows that

2.3 Simulation Analysis
Simulation analysis for the above test was carried out.
The analysis was based on the two-dimensional finiteelement method. The image of the analysis model isshown in Fig. 8.
In the analysis, EPS material and the concrete blockon the top were considered as plane strain, and theconcrete deck 100 mm thick in the middle was used as
the beam element. As shown in the lower left of Fig. 8,
joint elements were installed between the EPS blocks
and between the EPS blocks and the deck. In addition,
2 spring elements per block were installed between theEPS blocks which modeled the joint metal binders. Thespring value is shown in the figure, which is the value
set from the result of the trial by analysis. The boundary
condition of the analysis was fixed to the bottom as in
the test, and seismic motion was incident from this
fixed bottom.
For analysis, the large deformation analysis program
FLIP / TULIP was used. As a result of the analysis, Fig.
9 shows a comparison of the horizontal response
displacement at the top position (left end) of the modelwith the test results. In the analysis, there is a residual
behavior of the displacement after receiving a large
displacement, but the peak of displacement and themaximum displacement amount are almost same. Fig.
10. Shows the horizontal acceleration. The test andanalysis are almost in agreement. Similarly, the one

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showing vertical acceleration is Fig. 11. Except
short-period peaks around t = 7.8 sec according to thetest, they are almost same.
Thus, it was found from the analysis that not only thehorizontal direction but also the vertical vibration due
to rocking can be expressed. This confirms theapplicability of the analysis to seismic resistanceevaluation of large-scale EPS embankments andembankments of high importance.
RC Slab(Solid)
RC Slab(Beam)
Joint Element(Friction coefficientμ=1.0)：Spring Element(Joint Metal)
Normal Stiffness Kn=10kN/m
Shear Stiffness Ks=100kN/m)

EPS

JointMetal(Spring:2pieces/Block)

EPS Block

EPS Block

EPS Block

3 CONCLUSIONSIn this paper, full scale tests on resistance of EPS
embankment against large earthquake motions and its
analytical evaluation were described. The results are
summarized as follows;(1) The new joint metal bindings between the EPS
blocks developed for improving earthquake
resistance improve the seismic performance ofEPS embankment compared to the conventional
ones.
(2) Rocking deformation can be suppressed by thehybrid layout of joint metal binders whereconventional joint metal binders with both-sided
spikes are used for vertical connection of EPS
blocks and joint metal binders with one-sided
spikes are used for horizontal connection of EPS
blocks.
(3) Numerical analysis using a large deformation
analysis program FLIP/TULIP could be
successfully performed to simulate the shaking
table test behavior of EPS embankment including
the rocking behavior.

Joint Element(Friction between blocks)

REFERENCES
Fig. 8. Numerical Analysis Model
Table. 1. Physical Characteristics
Young'sPoisson's Unit VolumeWeight
ModulusRatioνγ (kN/m 3 ) Ｅ (kN/m 2 )EPS(D20)0.075
0.20
10,800MaterialDisplacement(mm)RC Slab

0.167

400

23.50 23,500,000

Top of embankment

2000-200

Test Result
Analysis-400
0510Time(sec)

15Fig.9. Horizontal displacement of the top of the embankment
Acceleration(gal)1000
Top of embankment
5000-500-1000
0Test ResultAnalysis
510Time(sec)

15Acceleration(gal)Fig. 10. Horizontal acceleration of the top of the embankment
2000
Top of embankment
10000-1000-20000

Test ResultAnalysis
510Time(sec)

15Fig. 11. Vertical acceleration of the top of the embankment

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