Unsteady Rheological Behavior of Liquefied Soil in Earthquake

Abstract

Unsteady rheological properties of liquefied soil in the Chiba-ken Toho-oki (East-off Chiba pref.) Earthquake were measured by means of parellel-plate rheometers. The size (the longest diameter) of the soil particle was distributed from 30 to 300 μm and the average was about 95 μm.
The soil shows a typical flow curve of a heterogeneous system having a yield stress. The yield stress of the soil suspension is proportional to c^7.7in the concentrations below 71 wt% and to c⁶⁷at the higher concentrations where the soil liquefies during the course of cyclic strain applications. The dynamic rigidity decreases to about 1/10 to 1/40 of the initial value by the cyclic strain.