Evaluation of hazardous effects of near-fault earthquakes on earth dams by using EL and TNL numerical methods (case studies: Gheshlagh Oleya and Jamishan dams)

Abstract

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.