Study On Control Criteria Of Stress And Integrity Safety Of Super-high Arch Dams

The strength and stability evaluation of super-high arch dams is an important and complex topic in arch dam design and research. In this dissertation, an effective FEM simulation evaluation system is established in order to reflect the actual stress state, analytical strength and stability characteristics based on analysis and comparasion of results of more than six super-high arch dams including Xiluodu, Jinping (I), Laxiwa, Dagangshan and Ertan by implying non-linear FEM, cantilever trial-load method and three-dimensional geo-mechanical modeling test. The main results are as follows:(1) Standards of Design specification for concrete arch dams in different nations are summaried and compared. By carefully dicussing the merits and dismerits of the normal analytical methods, the evaluation theories and the concepts of safety and stability of arch dams, a simulating evaluation system and its principles employing FEM are proposed considering both structural strength and integrity stability.(2) The considerable FEM standards of mesh generation, nonlinear constitutive model, yield criteria and evaluation system are proposed for high arch dam design. Based on the case of Xiluodu High-arch Dam, the sensitivity analysis of FEM is certified including of modeling grid, material parameters and water load.(3) By comparing analytical results of six super-high arch dams employing three methods mentioned above, dam body is divided into five different working parts and reasonable ranges of stress are proposed as control criteria of stress. Respectively, ranges of deformation and three assurance factors K1, K2 and K3 for evaluation of integrity stability employing overloading method is summarized.(4) A set of considerable failure modes are summarized by statistical analysis of fifty-two arch dams which were damaged or collapsed. A reasonable failure process observed in modeling test is detailedly described under overloading condition. The effective assurance factors K₁, K₂ in integrity analyis employing nonlinear FEM are reasoningly defined and described as the turning points of the failure evolvement by comparasion of results analyzed by nonlinear FEM and 3D geo-mechanism modeling test. The method to obtain K₁, K₂ and K₃ is also illustrated detailedly. Finally, the considerable values of K₁, K₂ and K₃ are proposd as control criteria of the integrity stability evaluation.