2020 Volume 15 Issue 4 Pages 683-695
Energy-Based Method (EBM) for liquefaction potential evaluation was previously proposed, wherein the total energy demand at a site is determined by upward wave energy. To make the most of the EBM already developed (the first stage evaluation), additional steps have been proposed to evaluate the liquefaction-induced strain and associated soil settlement using given earthquake wave energy by introducing a simple assumption that the wave energy is equally shared among the liquefied layers already selected in the first stage. By applying this to a uniform sand layer as well as case history sites, it has been found that the two-stage evaluation tends to calculate much higher liquefaction-induced strains than 7.5% in a smaller number of layers than the first stage. Furthermore, soil subsidence at the case history site has been calculated using a robust correlation of volumetric strain versus shear strain based on database of various intact soils. The ground surface subsidence thus calculated is found to be agreeable with post-earthquake observation at the same site. Thus, the newly developed two-stage EBM of liquefaction evaluation can predict not only the possibility of liquefaction but also the maximum induced strain in individual liquefied layers, and associated surface settlement without resorting to complicated nonlinear effective stress dynamic response analyses.
