Study On Reliability Analysis Method Of Deep Sliding Stability Of Gravity Dam

Gravity dam is one of the main dam types in water conservancy projects.Because the deep sliding of gravity dam is a common problem in practical engineering,it is of great significance and value to study the deep sliding stability of gravity dam.In this paper,by consulting the relevant literature,on the basis of summarizing the relevant methods of reliability analysis of deep sliding stability of gravity dam and the research status at home and abroad,aiming at the problem of deep sliding stability of double sliding surface,the reliability of deep sliding stability of gravity dam is studied.The main contents are as follows:(1)The finite element strength reduction method is used to reduce the strength parameters of two weak structural planes and sliding bedrock materials.The calculation convergence criterion,plastic zone penetration criterion,characteristic point displacement mutation criterion and characteristic point displacement change rate mutation criterion are used to calculate the deep sliding stability safety factor of gravity dam.The results show that the safety factors calculated by these four criteria are basically the same.(2)The surrogate model of deep sliding stability analysis of gravity dam is established by using Latin hypercube sampling and BP neural network,which is used to replace the finite element strength reduction method to calculate the safety factor of deep sliding stability of gravity dam.The orthogonal test method and EFAST method were used to analyze the sensitivity of the material strength parameters of the two weak structural planes and the bedrock between them in the deep sliding stability of the gravity dam.The results show that the greatest impact on the deep sliding stability of the gravity dam is the bedrock cohesion,followed by the bedrock friction coefficient.The friction coefficient of the upstream sliding structure surface may interact with one or more other factors to have a greater impact on the deep sliding of gravity dams.(3)According to the geometric meaning of reliability index,the optimization model of calculating reliability index is established,and the reliability analysis method of deep sliding stability of gravity dam based on particle swarm optimization algorithm is proposed.Through engineering examples,the calculation results of this method meet the accuracy requirements.(4)The influence of the distribution type of strength parameters of dam foundation materials on the reliability index is analyzed.The results show that when the distribution of strength parameters of all dam foundation materials is lognormal distribution,the corresponding reliability index is the largest.From the perspective of the dam foundation area where the material strength parameters belong,the change of the distribution type of the material strength parameters in the bedrock area has the greatest influence on the reliability index,followed by the downstream sliding structural surface,and the smallest is the upstream sliding structural surface.From the type of material strength parameters,the change of cohesion distribution type has greater influence on reliability index than friction coefficient,and the change of bedrock cohesion distribution type has more obvious influence on reliability index than that of structural surface cohesion distribution type.