Analysis Of Fatigue Damage Characteristics Of Concrete Gravity Dam Under Earthquake

Due to the increasing demand for energy in China,we have built a large number of hydropower stations in the southwestern region where water resources are abundant.The earthquakes in the southwestern region are frequent and the intensity is high.Concrete gravity dams may cause serious secondary disasters if they are damaged by earthquakes.Therefore,in order to ensure the seismic safety of concrete gravity dams,it is of great significance to carry out research on the damage characteristics of dam concrete.In this paper,a concrete gravity dam is taken as the research object,and a large number of numerical simulations are carried out on the dynamic response of the dam under earthquake and the fatigue damage characteristics of concrete.It reveals the damage distribution of dam concrete under earthquake action,the main work as follows.Firstly,using the finite element analysis software ANSYS to establish a finite element model of non-overflow dam section,the three-dimensional static analysis of a non-overflow dam section was carried out,and the displacement and stress-strain of the dam body under normal water storage conditions were analyzed.Second,the modal analysis of the non-overflow dam section is carried out to solve the natural frequency of the dam section in the empty and full reservoirs,and the natural vibration characteristics are analyzed to obtain the natural vibration period and vibration mode of the dam section.Third,the time-course dynamic method is applied to analyze the linear elastic dynamics of non-overflow dam sections,and the seismic response law of non-overflow dam sections under different working conditions is analyzed.The seismic weak areas of non-overflow dam sections are found out,and effective seismic strengthening measures are proposed.Fourth,the concrete plastic damage model is used to calculate the occurrence position,appearance range and crack development trend of dam body fatigue damage under different peak accelerations of koyna gravity dam and mold concrete gravity dam.And the fatigue damage distribution law of gravity dam is obtained.Fifith,the calculation model of low-cycle fatigue damage of concrete gravity dam concrete based on deformation modulus is proposed.According to the model,the cumulative damage area of low-cycle fatigue damage generated by the non-overflow dam section of gravity dam under different seismic peak accelerations is calculated.By comparing with the calculation results of concrete plastic damage model and the results of linear elastic dynamic analysis,the correctness of the model is verified.The research results of this paper have certain reference value for the fatigue damage check and seismic optimization design of concrete gravity dam.However,due to the earthquake,the dynamic response of the concrete gravity dam is very complicated.Some influencing factors are not considered in the numerical simulation.Therefore,the dynamic response and fatigue damage characteristics of the concrete gravity dam under earthquake action need further study.