Search Method for Critical Surface of Open-pit Slope Based on Minimum Reliability Index

In open-pit slope stability analysis, if rock parameters were treated as fixed values, a surface of minimum factor of safety could be searched. And the other one surface of minimum reliability index could also be located if rock parameters were treated as random variables. In this paper, The relationship between these two surfaces was investigated by reasonable weakening rock mechanical para meters and specific combinations of parameter values. An expedient technique was presented to locate the surface of minimum reliability index utilizing calculation of safety factor. The technique was examined by a case study. Results prove it is a practical and efficient technique to search for the critical probabilistic surface.