Structural Nonlinear Analysis Of Tunel Lining For High-Head Hydraulic Tunnels

Diversion tunnel is an important part of the system in hydraulic structure. In the design of large hydropower station, often we can meet design problem of tunnel with high water pressure and large diameter, especially in large water pumped-storage power station and type of high water head, corresponding large diameter of tunnel by hydraulic pressure construction start to increasing, the design of pressure tunnel also appears more and more important. Traditional calculation method of pressure tunnel assumpted lining materials for rock for isotropic elastic medium, has neglected the the adverse effects of surrounding rock and lining material nonlinear properties, and surrounding rock and lining structure is calculated separately, resulting in tunnel lining thickness of concrete of large quantity. Therefore, it is necessary to consider combined bearing of tunnel lining and rock by material nonlinearity circumstances in order to provide basis for lining tunnel in engineering practice and choose reasonable economic type of lining and increase safety degree.Firstly,l analysis practical engineering materia and calculate the boundary conditions. Using ANSYS finite element software to establish the integral model, considering of surrounding rock and lining, the outer layers and the inner lining of the contact between steel lining, use contact model of the point to point, Contac12 used respectively with Contac52 unit. During the initial stress and to the excavation of the secondary stress field after supporting analysis, Then in the maintenance of tunnel, water filling operation condition of the two lining form (single-layer reinforced concrete lining and the steel lined reinforced concrete lining), calculated with the combination of single lining lining conditions, outer reinforced concrete lining the stress, deformation, and the two lining form stress analysis, relevant conclusions.Secondly, using boundary value method and calculated the elastic mechanics method, and compares with the result of finite element method. By using finite element method, the method of elastic theory and the boundary value analysis of pressure tunnel calculation shows that:the finite element method, to a certain extent, overcome traditional methods of tunnel design flaws, can consider comprehensively complex geological conditions and load conditions.Through camparision,we can know that boundary value method and elastic mechanics method in the material properties,because of surrounding rock and lining interaction between do more with simplified assumption, only suitable for boundary condition and surrounding rock properties of relatively simple to complex geological section of pressure tunnel using these two kinds of methods are less finite element calculation results, and the higher pressur the more error.calculated results.