Energy-based liquefaction evaluation for induced strain and surface settlement ― evaluation steps and case studies ―

Abstract

Energy-Based Method (EBM) for liquefaction potential evaluation was previously developed by the present author, wherein the total demand compared with the capacity at a site can be given by earthquake upward SH-wave energy. To make the most of the EBM with the energy demand given, evaluations are added here to calculate the liquefaction-induced strain and associated soil settlement by introducing a simple assumption that the wave energy is equally shared among layers firstly determined as liquefiable. By applying this to a uniform sand layer as well as case history sites, the additional liquefaction evaluation tends to calculate much higher shear strains than 7.5% corresponding to initial liquefaction in a smaller number of layers than in the first stage. Furthermore, soil subsidence calculated using volumetric strain versus shear strain correlations for intact soils is found agreeable with actual performance during earthquakes. Thus, the two-stage EBM of liquefaction evaluation can practically predict not only liquefaction potential but also induced strain and surface settlement without resorting to nonlinear numerical analyses.