Comparison of Behavior of an Embankment Dam with Inclined and Vertical Cores using Numerical Analysis

Abstract

This article presents the results of static and dynamic numerical analyses of an existing embankment dam with an inclined clay core (Bidvaz Dam) in Iran. The analyses are repeated for the same dam, but with the assumption that the core is vertical. The results consist of displacements and pore water pressures within the dam core. The Mohr Coulomb elasto plastic model and an elastic model are considered for the dam and foundation materials, respectively. For the earthquake loading, nonlinear dynamic analyses are carried out. The seismic stability of the earth dams is evaluated using nonlinear displacement analyses, considering the accelerograph obtained by ground response analysis. The scaled Tabbas earthquake time history (1978) is employed as the input motion to the bedrock. The analyses for the earthquake loading are performed using the total strength parameters of the materials. The results of the analyses for both of the dams are carefully evaluated and compared. The results are summarized as follows: for the pre-earthquake (end of construction) loading, the deformations developed in the dam body are comparatively larger in the dam with the inclined core, while the excess pore water pressures in the core are comparatively higher in the dam with the vertical core; for the earthquake loading, the deformations developed in the dam body are comparatively larger for the dam with the inclined core; sensitivity analyses with various peak ground accelerations indicate that the dam with the inclined core is more susceptible to instability during earthquakes.