Safety level and reliability index for bank slope stability

Based on statistics and analysis of the safety factor of unstable bank slopes, the relation between safety level and reliability index of stability is studied and discussed, and then the elementary calibrating calculation is carried out to the levels of safety and reliability for bank slope stability in the range of safety factors stipulated in existing China Technical Specifications for Port Engineering - Foundation Part (1987) and to those reached by some stable bank slopes already built. The results show that the reliability index beta in the effective stress method is able to reach a high value of 2.4 similar to 4.1 (mid-value 3.25), while the value of beta in other three kinds of total stress method can just reach a lower value of 0.5 similar to 2.8 (mid-value 1.65), which are in conformity with the engineering experience in China, and thus acceptable. Some suggestions are also given in this paper to the adoption of the value of beta(0)-objective reliability index for bank slope stability.