Calculation of stability reliability of soft base controlled unstable rock and parameter sensitivity analysis

Abstract

There are a large number of unstable rocks whose stability are controlled by soft base layer in the mountainous areas of southwest China, and they have caused serious harm to people’s lives and local economic development. Therefore, it is of great practical significance to study the stability and failure mechanism of such unstable rock. Taking the in Wulong District, Chongqing as an example, this paper analyzes the failure probability and reliability index of the unstable rock under different conditions by use of Monte Carlo method and on this basis, the sensitivity of the stability of dangerous rock mass to the main influencing factors is analyzed. The results show that the stability coefficient, failure probability and reliability index of are equal to 1.151, 26.245% and 0.642 under natural condition. However, the stability coefficient of decreases rapidly and the reliability index and failure probability increase obviously when combined with other factors such as rainfall or earthquake. The sensitivities of the influencing factors of the unstable rock are from top to bottom internal friction angle of soft layer, the horizontal seismic force, the cohesion of soft layer, the water content in the crack and the weight of soft layer. The research results can provide some reference for the stability analysis and engineering prevention of such unstable rocks.