Study On Finite Element Analysis Of Arch Dam With Assumptions Of Arch-Cantilever Load Method

Arch dam is a type of economic and safe dams, and occupies an important position in the dam construction in Western China. At present, the arch dams that are under construction or proposed in our country, such as Xiluodu, Jinping, Baihetan, are in the 250m or more. The safety of high arch dam can not be ignored, once the accident comes, the national economy and people's lives will be confronted with a major threat, and even affects social stability. High arch dam has a thin shape, a very complex mechanism of force, and less engineering experience in the past. So it is very important to evaluate the stress state of the key parts of high arch dam, such as heel and abutment. The existing arch dam design sets the trial load method and the finite method as the main methods of stress analysis of arch dam. The trial load method assumed the load of arch dam is shared by arches and cantilevers. The stress state of arch dam is calculated by using the plane section assumption (in the strict, it should be the linear assumption of radial fibers). The stress results of arch dam that is calculated by using the triad load method is similar to the stress results of material mechanic. The triad load method is recommended by the existing norms, but it is lack of flexibility. The finite element method is easy and convenient for modeling and using. But there is stress concentration in the heel and the abutment of dam. And the calculated results are not stable with the different grid and cell types. In view of the finite element method and the trial load method with their respective advantages, we propose a set of finite element analysis with assumptions of arch-cantilever load method for stress analysis of arch dam.This paper firstly introduces the basic theory of the trial load method and the finite element method, then demonstrates the feasibility and necessity of finite element analysis of arch dam with assumptions of arch-cantilever load method. Taking the typical arch of Baihetan hydropower station as a case, this paper proposes two finite element analysis approaches with the linear assumption of radial fibers by using ANSYS. One is inserting rigid units between the nodes in the fibers, the other is introducing the displacement constraint equations. The distributions of displacements and stress of nodes in the constraint direction are a linear relationship, effectively easing the stress concentration of conventional finite element method. The feasibility of this method is verified with the comparison of structural mechanics simplified method. At the same time, the range of constraints of arch's fibers is discussed, and proposing a finite model with constraints only in the degree of freedom near the abutment where exists stress concentration.We select a single arch dam with equal thickness for finite element analysis of arch dam with assumptions of arch-cantilever load method, the tangential and vertical displacements of dam's fibers are restricted. The results show that the stress distribution in the tangential and vertical is a linear relationship, effectively easing the stress concentration of conventional finite element method. When the dam is meshed by solid45, the stress results of finite element analysis of arch dam with assumptions of arch-cantilever load method is consistent with those of the trial load method. On the correctness of both algorithms and software has played a role in mutual authentication. We discuss the sensitivity of grids and unit types in this method, and the stress results of this method is similar to the results of equivalent stress. So, the finite element analysis of arch dam with assumptions of arch-cantilever load method can be a new method for the stress analysis of arch dam, it has a certain research and engineering application value.