The Simulation And Analysis Of Concrete Gravity Dam's Seismic Response Based On Abaqus

Concrete gravity dam is an important dam type which is widely used. However, the existence of transverse joints weaken the overall stiffness of the concrete gravity dam, which often causes penetrating cracks in the upper section of the dam under earthquake action. The dynamic response of concrete gravity dam with transverse joints under severe earthquake is a complex nonlinear process, which is influenced by many factors, such as seismic waves, boundary conditions, hydrodynamic pressure and so on. In orde to understand the dynamic response law of concrete gravity dam under seismic loads comprehensively and systematically, and provide some reference for the engineering design, this paper uses the 3D whole dam model with more than one transverse joint as research object and uses the explicit finite element method in the time domain to solve the dynamic equations based on finite element software ABAQUS, studies on the simulation technology of the seismic response, analysis the effect of transverse joints on natural vibration properties and dynamic response of the gravity dam, and probes into the simulation method of high accuracy and high efficiency which can be applied in the modal analysis and seismic response analysis of ctoncrete gravity dam.The major work done in this paper is listed as following:(1)Six calculation models are designed for the study on the influence of the transverse joints, the reservoir water and the interaction with dam and dam foundation rock to the vibration performance of concrete gravity dam. The calculation results show that the transverse joints weaken the stiffness of the dam, which appears as the increase of the natural frequency, particularly the fundamental frequency; Compare with the reservoir empty model, it leads to increase the system quality and reduce the natural frequency of dam, especially the base frequency when considering the impact of the reservoir water. It will reduce the stiffness when the interaction between dam and foundation is studied as mutual contact, which makes the natural frequency of concrete gravity dam is relatively small compared to tie constraints.(2)Four algorithms are designed according to whether to consider the influence of transverse joints and the various simulation methods respectively to analysis the seismic response of the concrete gravity dam, study the change law of the dynamic displacements, the transverse joints aperture, the dynamic stress and the acceleration when using different simulation methods, explore the simulation method for the seismic performance analysis of concrete gravity dam which is more practical. The research indicates that the dynamic response of the model with transverse joints is significantly greater than that of integrated model, particularly the seismic response along transverse, which shows that the transverse joints can not be ignored in the analysis for the seismic responses of the concrete gravity dam; Conclusion from comparing betwween various simulation methods shows that the dynamic calculation results of single dam are too large; Besides, it is founded that the calculation results of the contact method are greater than the cohesive algorithm, which is reality-oriented because of the simulation of the true cross joint material and the consideration of the normal pulling stress.(3)The simulation method for static analysis of the concrete gravity dam is improved which realized for high efficiency and accuracy by the application of the sub-model technology in ABAQUS. It also gives a trial discussion of the application for this technology in the seismic response analysis of the concrete gravity dam. It saves the computing CPU time greatly, however, it also bring great errors. It is believed that it will come true for the application of the sub-model technology in the seismic response analysis of the concrete gravity dam when the subprograms or the combine with other software are applied.