Reliability Analyses Of Anti-sliding Stability Of Multi-slide Surface In Deep Bedrock

Instability risk analysis plays a very important role in the design of gravity dams,with the long-term improvement of the design specifications and construction technology of gravity dams,the current risk of destruction of gravity dam has been concentrated in the Deep Antisliding Stability of the dam foundation with many uncertainties.The structural reliability method is a common and international method for analyzing the stability of gravity dams.Usually,a typical dam section of a gravity dam is simplified as a plane problem.According to the geological conditions,the sliding surface is preset and the equal safety factor method in rigid body limit equilibrium method is used to obtain the reliable index ? of the engineering to determine whether the gravity dam meets the design and long-term function under the geological conditions.In the study of the reliability of the deep anti-sliding of the gravity dam,the calculation method of reliability,the processing of random variable parameters,and the establishment of the limit state mathematical model need to be discussed in more depth.With the help of intelligent optimization algorithm,system reliability calculation method,and fuzzy theory,this paper has carried out research in the following aspects:Firstly,consider the failure of the foundation of the gravity dam as multi-sliding surface failure,combine the actual engineering,solve the problem of reliability optimization as a minimum value according to the geometric meaning of the reliability index,and use the gravity distribution method and the equal safety factor method to construct a complex state equation when the failure of the foundation of the gravity dam is multi-sliding surface failure.An improved differential evolution algorithm(DE algorithm)is introduced to calculate its reliable index and to do sensitivity analysis of random parameters.The results verify the effectiveness of the algorithm.Secondly,considering the influence of the resistance angle between blocks in the dual sliding surface model of gravity dam,the sliding between the sliding blocks is regarded as the failure of the crack,and the three sliding surface model is formed together with the upstream and downstream sliding surfaces.The corresponding limit state equation is constructed,and the DE algorithm is used for calculation,and the reliability analysis under the condition that the second slip surface and the resistance angle are unknown.Thirdly,Considering the possible failure modes of multiple slip paths in deep dam foundation instability,with the help of the narrow-limit method,primary-secondary combination method and PNET method in the classical reliability calculation method,the dam foundation has multiple slip surfaces and multiple slip paths Calculation of system reliability;Fourth,considering the fuzzy of the random variables and the structural failure principle that affect the stability of the dam.Take the quasi-normal membership function when fuzzifying the random variable,and take the symmetric triangular membership function when fuzzifying the failure criterion,and analyze the influence of the form of membership function,the influence of the parameter value in membership function and the influence of the degree of membership on the results,combined with the narrow-limit method of system reliability to analyze the fuzzy system reliability of the gravity dam.Through the analysis and application of practical engineering,this paper provides a new reliable and effective algorithm for the existing structural reliability calculation system,and builds several complex forms of gravity dam structural reliability calculation models for research and analysis,and considers the fuzzy factors in the reliability calculation of gravity dam,provides new technical support for the further study of the gravity dam reliability.