Energy Capacity versus Liquefaction Strength Investigated by Cyclic Triaxial Tests on Intact Soils
Takaji Kokusho, Shunsuke Tanimoto
Abstract
A series of cyclic triaxial tests are performed on a number of intact soils sampled from various sites to examine their liquefaction behavior in terms of energy. Although several laboratory tests on reconstituted specimens carried out in cyclic simple shear tests have already shown that liquefaction behavior is uniquely determined by cumulative dissipated energy during cyclic loading irrespective of stress-time histories, it is found here that the energy capacity for liquefaction tends to vary depending on the cyclic stress ratio (CSR) or number of cycles for liquefaction (NL) in triaxial tests on intact soils of higher cyclic resistance ratio (CRR) in particular. This is found to be specific to cyclic triaxial tests wherein axial strains tend to grow larger on the extension side than on the compression side. In overcoming this unfavorable trend in view of in situ simple shear stress condition, a unique correlation between the energy capacity and CRR for NL=15 or 20 is developed by utilizing the test results, so that the liquefaction energy capacity to be used in the energy-based method (EBM) can be readily evaluated from CRR irrespective of soil types.