Earthquake stability assessment for open pit mine slopes

Abstract

Earthquake stability assessment of large open pit mine slopes brings together two areas of slope engineering that are usually quite separate. To account for the scale and nature of open pit slopes, analysis techniques widely used for small scale civil infrastructure slopes need to be adapted and then extended. The first part of this paper presents a framework for earthquake stability assessment of open pit mine slopes that has been used in practice by the authors. The framework attempts to provide consistency across various analysis techniques, from pseudo-static analysis to dynamic numerical modelling. Guidance is given for selecting an appropriate earthquake load coefficient for pseudo-static analysis. The second part of this paper presents two examples of dynamic numerical modelling. One example demonstrates that the earthquake response of large rock slopes is highly dependent on the interaction between the seismic hazard, the resonant behaviour of the slope and surrounding ground, the rock mass character, and the slope geometry, and it follows that understanding dynamic site response is an integral part of earthquake engineering for large rock slopes. The other example presents parts of a detailed analysis of slope stability and deformation, and compares the results to those obtained from simpler analysis methods.