The impact of considering the vertical seismic coefficient kv on the pseudostatic slope stability analysis of downstream tailings sand dams

Abstract

In Chile, the limit equilibrium analysis under pseudostatic conditions is compulsory according to the Supreme Decree 248 (DS248, 2007), which establishes a minimum factor of safety (FoS) of 1.2 for stability analysis. In Chilean geotechnical practice, it is usually considered just the horizontal seismic coefficient (kh) for the analyses. However, there is a constant discussion about the necessity of applying both horizontal and vertical seismic coefficient (kv) into the analyses. In addition, there is uncertainty about what kv/kh should be considered and the effect that the sense of application (upward or downward) could have on the FoS. This paper presents an analysis of the effect of considering different |kv|/kh from 0 to 1 on both analysis directions for generic downstream tailings sand dam. Based on this, different dam heights, beach lengths and seepage conditions are also analysed. The obtained results show that when both kh and kv are applied, the FoS increase if kv acts downward and decrease when it acts upward. In addition, the effect for |kv|/kh ≤ 0.5 is almost neglectable, especially for kh ≤ 0.15. Furthermore, although a short beach length significantly impacts the FoS, the influence of applying both kh and kv seems to be independent of the beach length.