Mechanism of Permanent Displacement of Ground Caused by Seismic Liquefaction

Abstract

This paper concerns with the mechanism of the permanent lateral displacement of ground induced by seismic liquefaction. The present study consists of three series of shaking table tests of both large and small scales. The test results demonstrated that the ground movement occurs in the same direction as that of the total head gradient as defined in hydraulics, while a large shear distortion occurs in the liquefied sand. The horizontal displacement in a liquefied layer was found to be null at the bottom and maximal at the ground water table. It was also observed that the surface unliquefied layer, if any, moved together with the liquefied subsoil without slip. The influence exerted by a global topography should not be neglected, although the local ground condition is important as well. The effect of the seismic inertia force is not important as compared with that of the gravity force. With these findings, it is suggested that the liquefied sand undergoing lateral displacement behaves similar to liquid. This idea seems to help predict the extent of the permanent displacement of the liquefied ground.