Empirical Model for Estimation of the Residual Strength of Liquefied Soil

An empirical model for the estimation of residual strength is proposed. The proposed model predicts residual strength as a nonlinear function of both penetration resistance and initial effective stress. The model is consistent with steady-state concepts and behavior observed in laboratory tests, but was calibrated on the basis of residual strengths back-calculated from flow-side case histories. The back-calculated strengths considered inertial effects, hydroplaning, uncertainties, the conditions under which flow sides are known not to have occurred in past earthquakes, and the relative quality of each case history. The proposed model predicts residual strengths that are generally between those predicted by direct approaches and those predicted by normalized strength approaches. The proposed model also allows estimation of the probability distribution of residual strength.