The mechanical parameters directly inferred from the results of experiments on rock strengths usually deviate to some extents from the real values.The factor of safety of a rock slope thus calculated using these mechanicals parameters is not able to reflect the actual stability of the slope.In this paper

the maximum likelihood estimation is used for the back analysis of the mechanical parameters of slip surfaces in rock slopes based on laboratory experiments and stability computation.The result shows that the probabilistic back analysis is more precise than from the regressive back analysis.This demonstrates that the present method can be reliably applied to slope stability analyses and design of rock slope supporting system.