Abstract:

Many earth dams are damaged by shearing under seismic stresses effect. In Algeria, earthquake of 21 May 2003, of magnitude Mm = 6.9 on Richter scale, considered as the most violent for more than 20 years, occurred about 70 km east of Algiers’s capital, where a large number of structures were damaged in this region. The aim of this article is to present a numerical analysis of an earth dam in the province of Oum-Elboughi. The objective is to show the influence of compressive seismic waves and the effect of foundation deph on dam behavior .The stady was carried out using a 2D finite difference method (FDM) using the FLAC 2D calculation code. In this analysis, a soil nonlinear behaviour is provided by a combined Hardin/Drnevich hysteretic damping behaviour model with Mohr–Coulomb elasto-plastic model. Results that are presented in terms of deformations and shear stresses developed at the dam and dam foundation show that the most critical area is located on the downstream side of the dam. Increasing the foundation depth decreases the value of horizontal stress, while decreasing it increases the dam instability risk.

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