Study On Dynamic Stability Of RCC Gravity Dam Based On Nonlinear Finite Element Method

With the social development and economic progress, China’s demand for energy become even more and more urgent. China is the world water conservancy country, and hydropower has advantages of low carbon and clean energy, so hydropower has a broad development prospect. Currently a large number of meter-class high dam is under construction and planning in the southwest region of China where it is a highly seismic region, the aseismic study of concrete gravity dam appears very important. Therefore this paper studied the dam’s aseismic based on a RCC dam project and made the following research:1) Boundary condition(BC) selected for foundation. Three BCs were studied such as massless rigid constraints foundation, viscoelastic boundary and infinite element boundary. With the verification of static and dynamic numerical example and comparison with elastic theory as well as related wave theory, it proved the BCs had been correctly implemented.2) Based on the elastic model, computing time-history response under seismic load of RCC gravity dam engineering under different BCs. Evaluate the response characteristics of different BCs and applicable conditions from the aspect of stress, displacement and dynamic stability. The results showed that the massless foundation showed a greater response result, viscoelastic boundary and infinite element boundary had a better energy absorption for seismic reflection wave and had an equal appearance on accuracy. However, it cost less time and had a higher computational efficiency in the infinite element boundary.3) A material nonlinearity was considered and cohesive behavior model was introduced to simulate the contact problems between the concrete layer and foundation weak structure plane.4) With stress results calculated by finite element method, using partial coefficient method recommended by design code and strength reduction method to evaluate the deep stability against sliding stability, analyze the security between RCC layers. Results showed that the safety factor calculated for the double-slip surface with total moment method was slightly larger than the equal safety coefficient method; The safety factor calculated with strength reduction method was close to the partial coefficient method. So the method to judge the dynamic stability should be considered comprehensive by the proposed methods.