A simplified method for the estimation of earthquake-induced pore pressures

A reliable assessment of liquefaction hazard is crucial for reducing the seismic risk of existing structures, especially for historical heritage. Common practice would need earthquakeinduced pore pressures to be evaluated through simple methods, such as uncoupled approaches. Uncoupled approaches based on undrained cyclic laboratory tests originate from Seed et al. (1975), where seismic induced rate of excess pore pressure build-up under fully-undrained conditions was added to the one-dimensional consolidation equation by Terzaghi. Despite its simplicity, this approach allows to consider the key features of liquefaction, as the influence of partially-drained conditions and pore pressures dissipation. In this paper, a simplified method based on Seed et al. (1975) is presented, aimed at estimating earthquake-induced pore water pressures. The governing equation is solved using the Finite Difference Method, by taking into account the dependence of soil stiffness on current mean effective stress. Different strategies for modelling the source term are presented and discussed.