Static And Dynamic Response Analysis Of High Arch Dams Based On Scaled Boundary Finite Element Method

In order to alleviate the shortage of energy and develop more renewable energy,a series of high arch dams have been built in the west of China.Most of the high arch dams in western China are located in high seismic intensity zones.Once damaged by strong earthquakes,they will have a significant impact on the safety of people and property in the downstream areas.Therefore,it is of great strategic significance to ensure the seismic safety of concrete high arch dams.Under actual seismic action,the upstream surface of arch dams is connected with the infinite reservoir,and the bottom is connected with the infinite foundation,the transverse joints will be sliding,opening and sticking.Therefore,we must consider the impact of dam transverse joints and treat the dam-reservoir-foundation as an open fluctuation system.Scaled boundary finite element method is a semi-analytical numerical method-It is superior to solve unbounded domain problems.Compared to FEM,the spatial dimension is reduced by one,because only the circumferential direction needs to be discretized.Compared to BEM,the fundamental solution is unrequested.However,SBFEM has not been extended to solve the 3D static/dynamic frictional contact problems.The purpose of this dissertation is that static and dynamic response analysis of high arch dams based on scaled boundary finite element method.This dissertation mainly focus on:an efficient algorithm to guarantee the continuity of interface with different feature,a new algorithm for static/dynamic contact problems of high arch dams with transverse joints,and a computing model with high efficiency and precision for high arch dams-reservoir-foundation system in time domain based on scaled boundary finite element method.This dissertation mainly includes the following aspects:1?A Mortar method based on SBFEM is proposed to address the continuity condition across the interface of different subdomain.By using this Mortar method,the interface meshes can be flexible divided and the transition between the coarse mesh and the fine mesh is easily,according to the computation requirement and the material characteristics.The numerical results show that the Mortar method based on SBFEM has a good accuracy and is convenient in practical application.2?In order to solve static and dynamic frictional contact problem,the scaled boundary finite element method combined with B differential equation method(SBFEM-BDE method)is proposed.In the proposed method,only the contact boundary need to be discretized,which reduces the spatial dimension by one.The SBFEM based on NURBS basis functions can exactly describe the geometry of contact boundary.The contact conditions are formulated as B differential equation and satisfied rigorously.The convergence of the algorithm to solve the B differential equation is guaranteed by the theory of mathematical programming.The Mortar method is used to implement the contact constraint,when the mesh across the contact boundary is nonconforming.Numerical results validate the effectiveness and accuracy of the proposed method.3.Based on scaled boundary finite element method,a computation model of the arch dam-reservoir-foundation system with transverse joints in time domain is established.In this model,the radiation damping of the infinite foundation,the water compressibility,the absorption of reservoir sediments,the Sommerfeld radiation condition and the key grooves of the transverse joints which will impact the response of arch dam are consider.Besides,only the dam-reservoir interface,the dam-foundation interface,and the surface of dam body need to be discretized in this model,which will reducing the workload of mesh generation,data storage and calculation time.A computation program,named NDAAD.TSB,is compiled which can calculate the static response of the arch dam with transverse joints and the dynamic response of the arch dam-reservoir-foundation system without transverse joints.The computation program is used to calculate the seismic response of a high arch dam which will be constructed,the results provide an important reference for seismic safety evaluation of the arch dam.