Abstract: Liquefaction of earth dams in plain areas with soft foundation of permeable layer poses a great threat to their safety. Previous liquefaction studies widely used in engineering were based on the stress of foundation soil, but this leads to a low accuracy due to the neglected effects of seismic load duration and randomness. This study presents an energy-based liquefaction discrimination method that calculates the normalized dissipated energy per unit soil volume and is implemented via finite element calculations for prediction of the liquefaction triggering possibility. We have verified the method using the historical records of soil liquefaction and achieved a good accuracy. In the case study of a plain reservoir, a three-dimensional model of its earth dam is constructed with the inclined incidence of ground motion being simulated, and the liquefaction region is predicted by this energy-based method. The results show its predictions improve significantly in comparison with the traditional stress method: the liquefaction locations are generally the same, both occurring at the dam toe and heel, but its ranges are more refined. Thus, our method would help theoretical and practical analysis of seismic liquefaction evaluation of earth dams in plain areas.

Key words: earth dam, seismic liquefaction, energy discrimination model, finite element analysis