Study On Earthquake Responses And Vibration-absorption Measures For Mountain Tunnel

Along with the implementation of West Development Strategy, a lot of tunnels for highways, railroads, and water and electricity projects will be built near the active faults or in the strong seismic regions. Does the dynamic response of mountain tunnel follow any rules under the strong earthquake? Is the tunnel safe when it is constructed near the active faults or in the strong seismic regions? How to make earthquake resistance and damping designs? All these are the concerned problems of project designer. The study of earthquake resistance design for the tunnel and underground engineering has just begun at present time in our nation. It is of great actual value to study the seismic responses and the vibration-absorption measures of the shallow buried mountain tunnel built in the strong seismic regions.First, the great data of the earthquake disaster for the tunnel and underground structure in home and abroad are analyzed. The summarizing the mode of failure, the influence factors and failure mechanism is conducted for the disaster occurred in the mountain tunnels. Then, the paper introduces the theoretical computer methods for the dynamic response of the tunnel and the underground structure. The problem of dynamic computation in the transverse direction of shallow buried mountain tunnel is studied as focal point. The problem is simplified as a circular lined tunnel in half-space. The series solutions for the scatting waves in half-space and lining under the actions of P wave and SV wave are derived by wave expansion method under the assumption of larger circular arc. And then, combining the boundary conditions, the problem of the tunnel dynamic response is reduced to the solution of a set of infinite algebraic equations. Finally, the dynamic responses of the shallow buried circular lined tunnel due to a vertical incident plane P wave are analyzed with a typical computing case.Then, for the numerical computation, the paper investigates the three basic problems, i.e. the deviation of earthquake integration displacement, the model boundary conditions and the model transverse scope for computation. With the software FLAC3D, the detail researches are carried out for the seismic response of the mountain tunnel body along with the buried depth, earthquake intensity, exciting direction, adjoining rock grade and lining rigidity. The results indicate that the mountain tunnel body often owns fairly high degree of safety during earthquake. So, aiming at the normal and uneven pressure entrance to the tunnels, the authors turn to give detailed and profound researches for the magnify effect of the slope surface and...