Seepage flow analysis in gravity and in variable acceleration fields

Some finite element approaches are discussed for the analysis of seepage flows in a gravity field (referred to as quasi static conditions) and in the presence of an acceleration field variable in time and space (i.e. during an earthquake). The equations governing the flow of a liquid within a porous skeleton in quasi static conditions and their finite element formulation are recalled first. In this case the problem can be solved considering the hydraulic head as the only nodal variable. Then the dynamic case is considered. The governing equations are combined in two differential equations that, reduced in their weak form, lead to three alternative finite element formulations. They involve different sets of nodal variables, namely: the components of the discharge velocity only; both velocity and pore pressure; the pore pressure only. The advantages and shortcomings of these solution procedures are discussed and, to validate them, a test examples is solved and compared with results presented in the literature.