Research On Fuzzy Reliability Of Anti-sliding Stability System Of Gravity Dam Foundation

Concrete gravity dam is one of the most common dam types in current hydraulic engineering projects.The stability analysis of the deep bedrock of the damhas always been a key problem in dam construction and its risk assessment.The problem of rock mass destruction in the deep layer of the dam foundation and its intricacy are in the category of system stability problems.In the study of the instability of the sliding channel of the dam body along the typical double slip surfaces or multiple slip surfaces in the deep layers of the bedrock,the limit state equation based on the safety factor method such as rigid body limit equilibrium is implicit and highly nonlinear The traditional checkpoint method is difficult to apply directly,and the second-order second moment(SORM)reliability method based on the difference principle can effectively solve this problem and calculate the reliability index of a single double-slope sliding channel.When the geological conditions of the gravity dam bedrock are relatively complex,and there are many multiple slip channels and the correlation such as common structural planes or the same material resistance characteristics among them,the bedrock must be considerated as a whole an unstable series system,and the reliability of the combined system is wide and narrow on the basis of the foregoing method.Boundary method,a set of new ideas for calculating the reliability of the gravity dam bedrock system.For the objective problem of various types of ambiguity in the structure,an effective fuzzy reliability research calculation method is proposed,and the corresponding Matlab reliability calculation codes are provided,and the typical engineering cases of gravity dam are studied and the single slip channel in the deep layer of the dam foundation and the overall stability system of the bedrock are analyzed at the same time..The main research contents of this paper are as follows:Firstly,the difference principle was introduced into the SORM method and used to calculate the reliability of the gravity dam under a single slip channel.At the same time,the influence of the differential step length ? on the reliability calculation of the gravity dam was studied and analyzed.In view of the fact that the shear resistance friction coefficient and cohesion in rock and soil generally follow different probability distribution types,in this paper,the SORM method based on the difference principle is improved,and the Nataf transform method is used to deal with the correlation between different distribution parameters in order to deal with the parameters Analysis and calculation of reliability.Secondly,based on the improved SORM method,a double sliding surface calculation is used to analyze the parameter sensitivity and calculate the correlation between the sliding channels.Combined with the wide and narrow boundary calculation system reliability,and the results obtained by Monte Carlo method are used to verify.Thirdly,the calculation model with multiple slip channels and the slip channels are multi-slip surface types is selected,considering the parameter ambiguity and correlation,and the structural limit state Z fuzzy.Equivalent probability density method is used to deal with fuzzy variables,and triangular membership function method is used to deal with the ambiguity of function.Combined with MC method to calculate the fuzzy reliability of the system,the influence of membership function on fuzzy reliability is discussed.