Role of Geometry and Stiffness Contrast on Stability of Open Pit Mines Struck by Earthquakes

Abstract

We develop a database containing 95 historical natural slope and 37 tailing dam failures triggered by earthquake. The database analyses show that earthquake-triggered failures in natural slopes are mostly initiated in the narrow ridges. We also collect published data on 177 open pit mines struck by earthquakes of which 85 mines are located in the seismically active areas. The database indicates no reportable failures triggered by earthquakes in the affected mines. We employ a finite element code to investigate the geometrical and stiffness contrast effects distinguishing the behavior of natural slopes and tailing dams from open pit slopes experiencing earthquake dynamic loading. It is concluded that narrow ridge and the top soil layer in natural slopes and the hill-shaped geometry and unconsolidated top later of tailing dams amplifies the horizontal peak ground velocity by factor of 8 compared to open pit mine slopes. Our numerical modeling of the rock slopes suggests that the typical pit geometry and the competent material in open pit mines boost the slope stability through decreasing the topographical amplification effects.