Seismic Analysis Of Circular Tunnel Structure Based On Elastic Wave Theory

Elastic wave scattering is one of the most important research topics in elastic dynamics disciplines, it is significance for geophysical prospecting, materials engineering of aeronautics and astronautics, civil engineering. Especially, the reserch that interface defects on the elastic wave scattering, is one of the most active field in applied mechanics.There are a variety of defects that the physical properties are discrete in natural medium and engineering composite materials, such as inclusions, holes, linings, cracks, etc. It will surely generate elastic waves in its interior when these natural medium and engineering composite materials are subjected to dynamic loads. These elastic waves will generate scattering waves when elastic waves encounter defects in process of propagation. The inverse problem of elastic wave scattering (analysis of inter-relationship between scattering waves and the geometry, orientation, size and physical properties of defects, or analysis of reversing the position, size of scattering body, the physical properties of surrounding medium and the information of reflected source on the premise that scattering effects of elastic wave are detected in the test) is great significance to the problems of elastic wave scattering by the defects of elastic medium in engineering domain such as mineral and oil exploration, non-destructive detecting of fixed quantity, radar, water sonar and blasting, ect.Based on circular tunnel structure as the research object, this paper discusses the tunnel lining elastic wave scattering and dynamic stress concentration, elastic wave sca ttering and dynamic stress concentration in subgrade plate, etc. This thesis mainly disc usses the following three questions.The first question is infinite circular lining in the underground space of elastic wave scattering and dynamic stress, based on the theory of elastic dynamics, using the wave function expansion method, research on tunnel lining shear elastic wave scattering and dynamic stress concentration, a general solution of the scattering field are presented.The second problem puts forward the structure model of half infinite circular tunnels in underground space, and the structure of elastic wave in the lining of multiple scattering and dynamic stress concentration problem are studied, to get the analytical solution of the problem, and gives the numerical solution of dynamic stress concentration factor around the lining. Semi-infinite border through the mirror image method to meet the stress free condition, using the cylindrical wave function expansion method shows the original image and the mirror image of the wave field analytical expression. Lining was analyzed through a numerical example and the boundary of distance and the number of incident wave on the lining around the influence of the dynamic stress concentration factor. The third problem puts forward the structure model of the circular tunnel in the board, the holes in the plate on the elastic wave and the subgrade of multiple scattering and dynamic stress concentration problem are studied. Mainly based on the theory of elastic dynamics, using the wave function expansion method, the subgrade of plate holes on shear elastic wave scattering and dynamic stress concentration, a general solution of the scattering field are presented.Finally, there is a brief discussion about the direction of further work.