Liquefaction potential evaluations: energy-based method versus stress-based method

A dataset of undrained cyclic triaxial tests for liquefaction with parametrically changing relative density and fines content is reviewed and interpreted in the scope of energy. It is found that the strain amplitude or pore-pressure buildup during cyclic loading is uniquely correlated not only to the energy dissipated in soil specimens, but also to strain energy given from outside. Hence, an energy-based method (EBM) is developed in which liquefaction potential can be evaluated by comparing strain energy for liquefaction in a sand layer with upcoming seismic energy without regard to the differences in seismic motions. Comparative studies in soil models demonstrate that the effect of various input motions is intrinsically included in EBM, whereas it has to be considered by choosing proper coefficients in a conventional stress-based method (SBM). Another significant difference is that liquefaction potential tends to be higher for a shallower depth in EBM, while it is vice versa in SBM in a uniform sand deposit.