Research Of Dam-Reservoir Interaction And Dam Isolations

Based on the theory of interaction of fluid-solid, The FEM and semi-analytic method are used to analyze the reaction of dam-reservoir subjected to seismic motion, the analysis includes the effect of water compressibility, reflectance of reservoir bottom and water viscosity. The mechanical properties, isolation mechanism and effects of hydraulic air cushions are studied theoretically. The plane-wave solution of the system of the fluid-gas-dam and the FEM model of gas isolations based on the state equation of ideal gas are presented for first time. Using this model, the technique feasibility to apply air cushions to Xiluodu high arch dam, located in Jinsajiang River, is explored deeply and demonstrated. The important results of scientific and practical significance are achieved.Based on the FEM model of the dam-reservoir system, the influence of water compressibility to the hydrodynamics is systemically analyzed and researched. It is showed thaf the water compressibility has significant effect to the size and distributing of hydrodynamics on the high dam, and the absorbency of reservoir bottom has a role as a damper on the dam-reservoir system. The semi-analysis method is used to analyze the relationship between hydrodynamics and the earthquake's frequency and the influence of surface wave on hydrodynamics. It is concluded that the earthquake's frequency has an important effect on the hydrodynamics, but the surface wave of water can be omitted in engineering design.In order to improve the numerical solution of coupled equation to the dam-reservoir interaction system, the high-precise integration is generalized from linear problem to the nonlinear one. This work promoted the development of high-precise integration applied to the coupled system of fluid-solid.The plane-wave analytic solution of the coupled fluid-air-solid system and the FEM model of air cushion isolations are applied to study the influence of air cushionon earthquake response of dams. The calculations show that air isolation will reduce the hydrodynamic pressure significantly and restrain the dam vibrations during earthquakes. If the dam and reservoir is isolated by air cushions, it will decrease the hydrodynamic pressures by more than 90% and the seismic stresses by 20-30%. The coefficient of anti-seismic safety will be risen from 0.93 to 3.58.This research is very valuable to improve the safety of high arch dams against strong earthquakes. It provides useful guidance for seism-resisting design of high arch dams subjected to earthquakes.