Study On Influence Of Bottom Sediment On Earthquake Response Of Concrete Dam

At present, There are a large number of high arch dams in the western high seismic intensity areas with complex geological conditions, and the seismic safety issue has become a key technology of engineering design. And a lot of sediment will be deposited in front of the dam after a period of time that the dam was built to run, which will have some impact on the seismic response. In order to explore the impact of the reservoir bottom sediment on the seismic response of concrete dam, this paper studied effects of sediment thickness, cohesion, internal friction angle and the porosity on the seismic response of concrete dam, which will provide useful relevant calculation parameters for seismic design. To conduct the study in this paper the following works have been done:(1) When choose a limited range to analyze in the infinite region, boundary processing should be done in order to solve foundation radiation damping effect. According to the movement solutions of elastic wave scattering field and viscous artificial boundary, the two-dimensional and three-dimensional viscoelastic artificial boundary equation have been got, which used to obtain the calculation method of viscoelastic artificial boundary springs and dampers parameters. The seismic waves used the artificial synthetic time curve, while research the techniques and methods of seismic input, which means that the wave would be about to be converted to the corresponding synthetic equivalent load and exerted on the artificial boundary nodes in order to achieve wave input, then verified by numerical examples of the calculation method, and the method is applied to study the sediment dam seismic response analysis.(2) This paper introduced the finite element analysis theory of coupling system of dam-reservoir water-sediment-foundation. From the introduction of fluid-structure coupling motion equations and its solution composed by motion equations of the fluid domain,the fluid domain boundary conditions, the equations of the dam motion and other components, to the control equations and boundary conditions of interface between the reservoir water, sediment and ground of reservoir water-sediment-ground system, and the theory which regarded the reservoir bottom sediment as the saturated liquid-solid two-phase of elastic-plastic porous medium. Then took a brief introduction of the large-scale nonlinear finite element software ADINA in CFD, structural analysis and fluid-solid coupling theory analysis module and FSI solver module, and finally based on a certain gravity dam and ADINA software, studied the impact of the seismic response, and the results shows that the sediment of certain thickness, the sediment shows inhibition to the seismic response with the increased sediment thickness.(3) Basing on a certain dam and the ADINA software to establish the fluid-solid coupling model of arch dam-reservoir water-sediment-foundation system, this paper studied the effects of physical parameters of sediment such as thickness, cohesion, internal friction angle and porosity to the seismic response, which would get some valuable outcomes for seismic design.