Fuzzy reliability analysis of slopes considering characteristics of membership function

With regard to the randomness, fuzziness and interval characteristics of geotechnical parameters of slope engineering, the scheme to select the cut set values of geotechnical parameters is proposed based on the distribution features of membership function and the cut set technique. The methods for expression of membership functions with different distribution forms and the determining methods for their boundary values are also proposed. Then the fuzzy reliability analysis method for slopes is established based on the cut set technique and the fuzzy point estimation method. The fuzzy reliability indexes of two typical slope examples are calculated under different conditions. The influence rules of distribution forms of membership function, selecting schemes of cut set values and boundary values of geotechnical parameters are analyzed according to the calculated results. The normal distribution and triangular distribution with ±2.5 times the standard deviation as the boundary values can be firstly used if the data size is not enough. The lognormal distribution and approximate normal distribution can be used secondly. The Beta (4, 3) distribution and Beta (4, 4) distribution will make the calculated results larger. The influences of boundary of cut set levels on the results can not be ignored. The cut set intervals for triangle, approximate normal and Beta (4, 3) distributions can be 0, 1.0. And it can be 0.05, 0.95 for the normal and lognormal distributions. Both the boundary and cut set levels with 0.1 interval should be used to calculate the fuzzy reliability indexes. The fuzzy reliability analysis method for slopes considering characteristics of membership function can make the calculated much more reasonable.