| The abutment aseismatic stability analysis of high arch dam built in seismic high intensity zones is a key problem of arch dam aseismatic design, which is encountered and must be solved carefully. In this paper, arch dam abutment .stability analysis is divided into three steps. First, the traditional rigid body limit equilibrium analysis is completed as primary calculation, which is concise and is widely used at present for engineering experince. Secondly, time domain explicit finite element method and rigid body limit equilibrium analysis are combined to solve the abutment dynamic stability, in which the block surface FEM node stresses are integrated to obtain arch push force time history and block earthquake inertia force. Therefore, the safety factor of body is a time history and can be used for reference for designers. Thirdly, arch dam and its foundation is regarded as a research object, with contraction joints in concrete arch dams and fault, fissure in rock foundation. In this stage, dam strength and abutment stability are considered as a uniform processes. Arch dam abutment stability is estimated by dynamic responses in arch dam. The completed main studies based on above-mentioned steps are as follows: Limit equilibrium formulae are given for wedge-shaped and multi-gliding surface body, Limit equilibrium analysis steps are pointed out and an engineering example of Xiluodu Arch Dam is given to show the ability of solving practice engineering. The method combined the time domain explicit finite element and rigid body limit equilibrium analysis is present, the basic formulae for FEM , arch push force and block body earthquake load are obtained. Xiaowan Arch Dam Abutment dynamic stability is calculated based on the combined method. Base on a Single-Degree-of-Freedom System response under the earthquake loading, a new time domain method solving the artificial earthquake waves compatible with object response spectra is presented, which has high convergence precision and the high calculation efficiency. The basic principle and method of automatic mesh generation for arch dam system isgiven, the basic formulations for mesh generation are established. The technique is combined with CAD, which can suit the complicated topography and geological conditions. The automatic mesh for Xiaowan, Long Yangxia and Da Gangshan arch dam and their foundation are given to demonstrate the practical application. *> The Discontinuous Deformation Analysis with Lagrange Multiply (LDDA) is introduced . and implemented in a finite element computer program. The calculation formulae fordisplacement, velocity and acceleration are established, the theory of Rayleigh damping and the experience formula on calculation time step is also given.> A new iterative algorithm for dynamic contact force is introduced, in which the relax factor is chosen by physical character not mathematic theory. The application example indicates the algorithm high calculating efficiency.> Successive Over Relaxation (SOR) algorithm with non-zero storage stiffness matrix is given for static solution. The SOR algorithm is much faster than static and dynamic combination algorithm used in Ref. 84 and Ref. 99.> A free field input method for arch dam seismic response with viscous dashpots and elastic springs is introduced, the comparative studies among the present method, transmitting boundary finite element and ADAPCH89 are completed, the present method and transmitting boundary finite element is closer than the ADAPCH89. The infinite media damping makes dam arch stresses and beam stresses depress obviously, and arch dam contraction joints make arch stresses further reduce, but arch stresses increase a little. Free field material damping has lightly effect on dam dynamic responses.> In personal computer (HP d530, Pentium ? 4 CPU 2.80GHz, 1GB memory), a dynamic calculation for Dagangshan arch dam and foundation system needs 98 minutes, and the analysis for dam with 15 contraction joints and foundation needs 7hours and 6 minutes. Under the same condition, above-mention calculation using time domain finite element with transmitting boundary needs 24 hours and 36 hours respectively. It shows the present theory, algorithm and computer program have high calculation efficiency.
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