Research On Static And Dynamic Behaviors Of Concrete Face Rockfill Dam On Deep Overburden Layer And Earthquake Liquefaction Of Dam Foundation

Concrete face rockfill dams (CFRD) have good adaptability for deformation and stability for seismic resistance, which are very suitable for building on deep overburden layer in the earthquake area. Combined with the project of Xieka CFRD locating on deep overburden layer, and by use of three-dimensional nonlinear finite element method to the static and dynamic state and the liquefaction possibility of powder sand soil in the dam foundation are deeply studied and also the corresponding reinforcement measures to put forword. The main contents are as follows:(1) According to the actual situation of Xieka CFRD, the dam construction process and the impoundment process are simulated in detail with the 3-D nonlinear finite element methods and classification loading techniques. The displacement and stress of the dam body, anti-seepage wall, concrete-face, peripheral joint, facing joint and so on are obtained. It is shown that the stress and deformation of the dam are conformed to the general law, and the numerical value is in the acceptable range, though the geologic engineering condition of the dam location is complex and overburden layer is thick. It is proved that the design of the dam is rational and feasible.(2) The analysis model of earthquake response and permanent deformation of dam is established with the 3-D nonlinear FEM in considering the Xieka project with the complicated terrain and geologic engineering condition and deep overburden layer and the distribution of powder sand soil in dam foundation. The earthquake response characteristic and its general law of body and joint are analyzed in detail under the effect of design earthquake, including acceleration response, the displacement reaction, the stress response and so on. The results indicate that the earthquake response characteristics of dam are conformed to the general law, and the dam is safe when subjected to the earthquake. Design code requirements are satisfied.(3) The growth model of pore water pressure in sand soil and the research results of earthquake liquefaction are studied, a analysis and apprised computer program is developed which is applied for the calculation of the possibility of earthquake liquefaction of powder sand soil in dam foundation of Xieka project. It's shown that the earthquake liquefaction of the project does not happen under the effects of seismic intensity of 7 degrees, while some liquefaction areas on the surface of the dam foot and reservoir bottom appear under the effects of seismic intensity of 8.3 degrees. And the reinforcement measure is proposed.