Dynamic analysis of rock slopes using the distinct element method: A case study at the right abutment of the Upper Gotvand Dam, Iran

This paper reviews the dynamic stability of the right abutment of the Gotvand Dam, the highest earth fill dam located at the southwest of Iran, using the distinct element method. The right abutment comprises a soft clayey layer called the Lower Mudstone Siltstone interlayer (LMST) covered by disturbed conglomerate blocks. According to the results of the dynamic numerical analyses, no collapse will occur at the right abutment area. However, the residual shear displacement of disturbed blocks on the LMST layer will be 20-60 fcm for Maximum Credible Earthquake (MCE) loading. Such a displacement can cause cracking in the cut-off wall, and hence it was considered the main indicator of the right abutment instability. Investigating different solutions, such as buttressing and excavation, showed that these approaches are not effectively preventing abutment shear displacement. Therefore, the designing process was carried out by accepting the risk of cut-off wall cracking in seismic loading conditions. However, some pre-remedial solutions (as discussed thoroughly in the text) have been considered in the construction process to minimize the risk of water seepage from the cut-off wall.