Influence Of Irregular Reservoir Shape On Hydrodynamic Pressure Of Gravity And Arch Dams

In order to solve the problem of energy shortage for China's sustainable development,hydropower,as one of the renewable and environmental energy,is playing a significant role.In the west of China,which is rich in water resources,a large number of water conservancy and hydropower projects have been built.With the construction of some world high dams,the seismic safety requirements of dams are becoming higher.The research shows that the dam-water coupling has an important effect on the dynamic characteristics of the dam under seismic excitation.Therefore,the study on the hydrodynamic pressure is of great significance to the seismic design and safety evaluation of dams.In this paper,based on the theory of the scaled boundary finite element method,aiming at the irregularity existing in the upstream near-field finite reservoir,the computation model of hydrodynamic pressure coupled with the finite reservoir and the infinite reservoir is established,and the coupled dynamic response analysis of dam-reservoir system is realized.The major contents are as follows:(1)Based on SBFEM,considering the compressibility of fluid,the absorption effect of reservoir bottom and bank slope,and by the weighted residual method,a 3d computation model is proposed for hydrodynamic pressure in finite and frequency domain.At the same time,the hydrodynamic pressure of different shapes of water(sphere,cuboid and the shape of L),different seismic frequencies and different seismic directions are analyzed,and the results of ADINA finite element method are compared to verify the accuracy of the calculation method.For the model,only the boundary surface of the finite domain needs to be discretized,the number of degrees of freedom is greatly reduced,and the computational efficiency is improved.(2)The coupling computation model is established for the irregular finite reservoir and the regular infinite reservoir.What's more,to accurately simulate wave propagation and dissipation,put forward a kind of no reflection of nonlocal and artificial boundary and discuss the effect of different excitation frequencies,different shapes of river valley(regularity,L shape,U shape)on the size and distribution of the hydrodynamic pressure acting on the dam.The results show that the shape of river valley does not change the distribution of dynamic water pressure,but affects the magnitude of hydrodynamic pressure.(3)SBFEM computation model of hydrodynamic pressure is combined with FEM model of dam structure to establish dynamic interaction model of dam-reservoir water system.The hydrodynamic pressure and dynamic response(displacement,velocity and acceleration)are analyzed under different seismic directions and several numerical examples including Koyna gravity dam with a rigid surface and Morrow point arch dam are provided.It is found that the vertical response of the crown cantilever is significant when the seismic excitation is vertical.When the seismic excitation is longitudinal,the horizontal response of the dam surface is obvious.The response of the dam surface is small when the direction is transversal.