Reliability Analysis of 3D Rockfill Dam Slope Stability Based on the Copula Function

The evaluation of slope stability reliability under the condition of incomplete probability information is one of the most popular issues in geotechnical engineering. The key difficulty in the issue lies in how to effectively establish a joint probability distribution model that conforms to the distribution characteristics of shear strength parameters under the condition of incomplete probability information. In this paper, based on the incomplete probability information of the nonlinear strength parameters of rockfill, the joint distribution model of the nonlinear strength parameters will be established using the Copula function. Combined with a radial basis function network (RBFN), an intelligent response surface method for reliability analysis of rockfill dam slope stability systems will be proposed. Its feasibility and validity will be demonstrated through an example. The influences of the Copula function type and sample number on the reliability of the stability system of rockfill dam slope will be systematically studied based on the constructed intelligent response surface. The results indicate that the Copula function could reasonably describe the correlated, nonnormal distribution characteristics of the nonlinear strength parameters and effectively construct their joint distribution model. The Copula function could provide reliable, statistically significant parameter samples for reliability analysis of the stability system of rockfill dam slopes. The traditional independent normal distribution ignores the correlated, nonnormal distribution characteristics of the nonlinear strength parameters of the rockfill, which result in the smaller failure probability and overestimation on the reliability of the stability system of the dam slope. The Copula function type and the number of samples have a significant impact on the reliability of the stability system of a rockfill dam slope. Therefore, it is recommended that as much test data as possible is obtained for statistical analysis, and the optimal marginal distribution function and Copula function are selected to improve the accuracy of the failure probability analysis of the rockfill dam slope stability system, which is of great engineering significance in the safety evaluation of a dam. (c) 2021 American Society of Civil Engineers.