Pore Pressure Generation of Liquefiable Soil Subjected to Irregular Cyclic Loading

抄録

Currently available liquefaction triggering assessment method uses charts correlating the cyclic stress ratio and soil resistance to liquefaction initially developed by Seed and Idriss (1971). The shear stresses imposed on the soil during an earthquake are irregular in nature and transformed into an equivalent uniform shear stress, t_eq, based on its maximum shear stress, t_max, and coefficient of equivalent shear stress, c_t (e.g., t_eq = c_t×t_max, JRA, 1995). The coefficient was derived mostly from experimental data conducted on clean sand. It is needed to study further on other soil types; however, it is rather difficult to experimentally investigate response of many types of soils for many earthquake waves. An excess pore pressure prediction method has been proposed by Okamura (2022), which is simple and based only on the fundamental law of soil mechanics. This paper presents the capability of the model to predict the liquefaction triggering for irregular cyclic loading. A series of undrained cyclic triaxial tests with irregular loading were conducted, and the results are compared with those predicted by the model. It was confirmed that the model predicted the pore pressure generation and liquefaction triggering reasonably well.