Numerical Simulation Of Live Of The Tunnel Seismic Fault Zones

In recent years, the tunnel project has been becoming important in the West-China engineering construction. Because the geological condition is complex, and the seismic phenomena emerges frequently, the anti-seismic problem of tunnel has become one of the important problems in West-China engineering construction. Based on the studying of Huangcaoping tunnel that locates in the Sichuan-Tibet road, the anti-seismic numerical simulation has been done by using FLAC3D. The contents of this paper mainly have the following sections.1. Taking example of some part of the tunnel, some basic problems of earthquake dynamic response in the numerical simulation have been discussed, and the numerical simulation calculation affected by the baseline correction , the transverse calculation scope , earthquake intensity , artificial boundary condition and the type of the seismic wave have been discussed. The seismic wave has been baseline corrected by using the method of least square and the software of Origin. Comparing the displacement value has proved the importance of baseline correction. In order to make certain of the reasonable transverse calculation range and the earthquake intensity, the transverse calculation range of four, six and eight times of the diameter and the seismic wave exceed probability of five, ten and sixty-three percent have been simulated. The difference between the free-field boundary and the viscous boundary condition has been discussed. Using these two boundaries, P wave and S wave has been comparatively analysed, and the reasonable artificial boundary condition has been gotten.2.In the action of P wave and S wave situation, the seismic dynamic response characteristic of this tunnel body has been discussed from the plasticity zone, displacement and stress aspects. The result shows that some parts of the surrounding rock in the tunnel has the possibility of shear failure, and the strengthening support measure should be done to a certian extent,while the supporting structure of the tunnel is safe.3.Under the effect of P wave and S wave, at No.1 and No.2 tunnel entrance segment, the seismic dynamic response has been seriously studied. The result shows that the slope of the tunnel entrance has the possibility of tensile failure, which will affect the safety of tunnel and slope, while the supporting structure of the tunnel is safe.