To study the effectiveness and design method of steel sheet pile wall supports driven at both edges of an embankment as a countermeasure against liquefaction of foundation, numerical analysis using an effective stress analysis method, LIQCA (Oka et al., 1994), was carried out. First, the applicability of the method to this type of problem was examined through comparison with the experiments conducted under 1 G field. Next, analysis was made on a full scale embankment including a case without countermeasure and 4 cases with the countermeasure.
In this section, the applicability of the method to this type of problem is examined through comparison with the shaking table tests conducted under 1 G field (Okamura et al., 1998; Case 4:Input motion=5Hz, 20waves, maximum acceleration 400gal, Thickness of sheet pile, t=4.5mm).
Numerical model is shown in Fig. 1. The soil structures (embankment and basic ground) were modeled by non-liner solid elements. The sheet pile wall was modeled by linear beam elements and the bottom of the sheet pile wall is fixed. The model parameters used are shown in Table 1. These parameters were determined from the results of the cyclic triaxial tests, drained triaxial compression test and so on.
Fig. 2 compares the calculated and measured time histories. Regarding response acceleration, Fig. 2(a) suggests as follows:
There is neither amplification nor damping in the acceleration response beneath the embankment (A2) in which the mean effective stresses are not reduced, and there is slight amplification at the top of embankment (A3) and computed results are in agreement with the test results.
On the other hand, there is de-amplification in the measured acceleration at the ground surface (A4) contrary to the simulated result.
