The Statistic Analysis And Reliability Research Of Rock Slope Stability

The value of stable angle of rock slope is controlled by internal structural planes of rock mass, and rationality of value directly affects the stability of slope. Currently, stereographic projection and limiting equilibrium theory are the main methods to determine the value. Practice shows that, these two methods both have certain limitations where a scientific equilibrium can't be obtained economically and safely. To this point, a series of probability statistics analysis are performed after calculating the data of structural planes of rock slope. Combining reliability theory, predictive value of safe slope angle with relatively low probability of failure is gained, and a specific approach is built to obtain the value of safe slope angle of rock slope.In this paper, 29 windows of total 11 mine pits in Laohuding Mining area in Jixian County, Tianjin City were selected for analyzing. 8138 groups of structural datum were investigated. Combined the dynamic analysis for various windows of structural planes of rock slope with the self-made program KINEM, the plunging direction, plunge and safe slope angle of probable sliding wedge are calculated. Meanwhile the value of safe slope angel was fitted by the program GODFIT to figure out the distribution curve and related parameters.Through Bayes statistical thought, the safe slope angle values of the windows with the same lithology were integrated together as the priori information of Bayes statistical analysis. The Bayes estimation formula for the safe slope angle are derived which respectively follow normal distribution, GAMMA distribution, exponential distribution and lognormal distribution. In addition for examples corresponding to the four distributions respectively are selected for key research. And the safe slope angles of the whole samples and the key-research samplers (25°～60°) were analyzed to get the two kinds of samples information of Bayes estimation values respectively under the four distributions.Reliability analysis is carried out using Monte-Carlo method to calculate the probability of failure and reliability index of estimation value of samples. A practical and simple computation method of slope is proposed and then the estimation value of safety angle of slope is calculated. The results show that the Bayes eastimated value of safe slope angle is a much more optimal value in economy and safety. This method can be applied in practical engineering.