The main framework of the current study is the dynamic time-history analyses by applying
actual near-fault earthquake records to the bedrocks of Gheshlagh Oleya and Jamishan
earth dams in Kermanshah province in west of Iran, by the use of two-dimensional (2D)
finite element method. The 2D plane-strain analyses using numerical methods of equivalent-
linear (EL) and true nonlinear (TNL) methods have been on the agenda. In order to
derive and compare acceleration and permanent displacement responses of the dam body
and it’s foundation, the 2D-FEA has been conducted. The excess pore water pressure function
(i.e., EPWPF) is defined with two forms consistent with EL and TNL methods. The
nonlinear analyses will find real definition when the excess pore water pressure function
provides fully coupled conditions that consider the solid displacement (u), pore water pressure
(p) and fluid displacement (U), simultaneously, i.e., u–p–U formulation. Obtained
results show that EL dynamic analysis method is not capable to model the side effects of
pore water pressure generation during the incidence of dynamic stress–strain, thus it is
considered as uncoupled method. From the other side, the TNL method shows more consistency
with the coupled fluid-mechanical calculations and models the seismic hysteresis
shear stress–strain behavior of the dam body, in a more sophisticated form.