Tunnel Intensity And FEM Analysis Of Seismic Response About Tunnel Structure

The strength theory of rock material is an important subject in tunnel structure research. For a century, people make a great deal of theory research and experiment demonstrate in the field of the strength theory of rock material. The Mises yield criterion, Tresca yield criterion and twin shear yield criterion are often used to investigate the various problem. However, it is obvious that some yield criterion, such as Mises criterion and Tresca criterion just apply to the material of the same tension compression yield strength and inapplicable for the rock material. Therefore a series of strength theory such as Mohr-Coulomb strength theory and unified strength theory which considering SD effect and intermediate principal stress can reflect real strength capability of rock material in complex stress condition. In aspect of earthquake-resistance, because there are few understanding about tunnel's earthquake action mechanism at present and the seismic design standard mainly pauses in the simple inertia load principle, so adopting new strength theory to perform the structure analysis has an important significance both in theory and practical application.The surrounding rock and lining are taken as the focus of this study. The unified strength theory is adopted as the strength criterion for the rock material. Supposing plastic volume strain do not equal zero, considering hydrostatic pressure and crack area in the lining, the elasto-plastic analysis is carried out to the tunnel structure and the resistance coefficient of adjoining rock is deduced. In addition, the characteristics of the failure mechanism of tunnel under earthquake are summarized. Taking Qinlingâ…¢tunnel as an example, the dynamic response of the tunnel structure are analyzed based on ANSYS software. The effects of different surrounding rock, different angle of incidence earthquake wave and the mortar anchor arm layer are investigated and discussed.The result indicates that in the elasto-plastic analysis of tunnel structure, plastic volume strain equal zero come to existence just in a certain circumstance. The obtained formula in this thesis compare to Fenner and Kastner formula has the universality, from which the stress field and displacement field under various conditions can be obtained by choosing different material parameter. The properties of surrounding rocks have great influences on the response of the tunnel structures. With the increase of the properties of rock, the surrounding rock undertaken the majority of loads, moreover the distortion and the stress of lining reduce gradually. Mortar anchor arm layer has great influence on the side wall of the tunnel and the stress can be reduced. The earthquake-resistances can be improved by using the mortar anchor arm layer. The diagonal earthquake compare with horizontal earthquake function has more harmful to the structure. The maximum principal stress and deformation are more likely occurred on the arch crown, the abutment wall. More attention should be paid to these parts in the design and construction of the tunnel.