Simple Method of Analysis for Liquefaction of Sand Deposits During Earthquakes

ABSTRACT Effects of irregular series of earthquake-induced cyclic stresses and the K0-value at the time of consolidation on the liquefaction resistance of sand are discussed by examining the results of several series of cyclic triaxial tests that have been performed at the University of Tokyo. Relationships are established in a graphical form between the applied shear stress and the residual pore water pressure, that is, the pore water pressure which remains after through application of irregular time histories of shear stress. On the basis of these relationships, with the effects of irregularity of wave form and the Ko-value being incorporated, a practical method is proposed to evaluate pore water pressures as well as factor of safety against liquefaction that can develop in a horizontal deposit during an earthquake. The method is applied to analyze the liquefaction of a sand deposit in Niigata where a detailed investigation was recently carried out for cyclic strength of undisturbed samples.