Centrifuge Modeling of Seismic Performance of Reinforced Earth Structures - Reinforced Soil Engineering: Advances in Research and Practice - page 419

Figure 6 Schematic drawing of model facing plate. (From Takahashi et al., 2001.)

surface of the ground. This compaction of the wall part was continued up to the
top level of the reinforced soil wall.
Having prepared the model, the container was set on the shaking table
mounted on the centrifuge and the centrifugal acceleration was increased
gradually up to 50 g. Confirming the rate of settlement due to the centrifugation
was negligible, shaking tests were conducted by inputting sinusoidal waves with
a frequency of 100 Hz, which is equivalent to 2 Hz in the prototype scale, to the
shaking table. Four waves with different conditions were input to each model.
Typical time histories of the input sinusoidal waves are shown in the prototype
scale in Fig. 7. During the shaking tests, acceleration and displacement of the
earth wall and the tensile strain of the geogrid were measured at the locations
shown in Fig. 3 . Photographs were taken before and after shaking to observe the
displacement of targets on the front surface of the reinforced soil.

3.1.2 Test Conditions

Results of seven centrifuge tests with different conditions are shown. The height
of the reinforced soil wall was fixed for all tests, namely 150mm, 7.5 m in the
prototype scale. The length of geogrids (L), spacing (s), and dry density (r d ) are
the variable parameters in the tests. The effects of each parameter on the
permanent deformation and dynamic response of reinforced earth wall were
studied. Table 6 gives the test conditions The first letter in the test code

1.40Mg/m 3 and 1.48Mg/m 3 ,
respectively. One tenth of the first number after the letter in the code corresponds
to the length of the geogrid in the prototype scale and one hundredth of the second
number grid spacing. The natural frequencies measured using a random wave
with small intensity before shaking tests were around 140 Hz and 180 Hz for the
model r d ¼

means the density, namely “L” and “D” are r d ¼

1.40Mg/m 3 and 1.48Mg/m 3 respectively, which are 2.8 Hz and
3.6 Hz in prototype scale. The measured natural frequency was not dependent on