Elasto-plastic FEM Analysis Of Dynamic Response Of High Earth-rockfill Dams During Earthquake

The earth-rockfill dam is the most common type of dams in the world. With the development of the water and hydropower resources, the heights of some earth-rockfill dams reach over 200~300m, and most of these dams are located in the southwest of China where earthquakes happen frequently. It is a serious threat to the people's lives and property if dams damage due to earthquake. So it is quite significant to study dynamic response of high earth-rockfill dams for the dam design and safety evaluation. In this dissertation, numerical calculations were performed to study the dynamic response of high earth-rockfill dams, and the main research works and conclusions are summarized as follows.The dynamic analysis is based on the initial static stress filed, which is carried out using Duncan-Chang's E-B model in this paper. Then both 2-dimensional and 3-dimensional dynamic calculations of a high earth-rockfill dam during earthquake are conducted with the program EB3D in traditional way of visco-elastic model and equivalent linear method. Variations of residual deformation, effective stress and response acceleration during earthquake were analyzed, and the limitations of the traditional way were discussed as well.Then the dynamic response of the high earth-rockfill dam in the whole process of earthquake was analyzed with a program FEMEPDYN, which is based on elasto-plastic model and nonlinear method. Theoretically this method is more reasonable, but this program cannot be used in the calculation directly because of lack of static calculation. The unreasonable initial static stress field usually causes non-convergence of calculation, therefore improvements were made in FEMEPDYN for stress pretreatment, and the performance of the calculation was rather improved. The dynamic behavior of the high earth-rockfill dam during the earthquake was analyzed 2-dimensionally and 3-dimensionally, and the characteristics of response were investigated, including acceleration, effective stress, excess pore water pressure, residual deformation of the dam and so on. According to comparisons with practical projects and traditional methods, it is shown that the new way is reasonable in describing the dynamic response of high earth-rockfill dam during earthquake. Furthermore, 2-dimensional calculation of another high earth-rockfill dam on alluvium was carried out in the new way to analyze the dynamic response in complex conditions during earthquake.Although the elasto-plastic model and nonlinear method is still lack of much more verifications of the prototype or model tests at present, and more experience is need for the determination of material parameters. However during to the complete theoretical framework, it will become the mainstream for analyzing dynamic response of high earth-rockfill dam during earthquake.