Simulation Study Of Complex Wave Field Characteristic About Weak Geologic Bodyin Tunnel

Tunnel project is a hidden high-risk projects, geological disasters are often accompanied by the construction of the tunnel, the tunnel in front of poor geological body (such as faults, weak, broken belt, gas, water, etc.) often lead to a variety of accidents, so the front of the construction on the working face of adverse geological prediction, forecasting is particularly important.But up to now in the tunnel ahead of the overall level of prediction is still under development, forecasting accuracy and reliability to be improved, need to be further improved and perfected. In practice, the seismic reflection method on tunnel prediction ahead of the more widely used, account for a large proportion of,and seismic wave field is very complex and superimposed on each other, is difficult to effectively identify and isolate, so this tunnel seismic reflection method a preliminary theory study and discussion. Use a variety of visualization software developed for a variety of adverse geological tunnel wave forward modeling program to simulate the tunnel in front of adverse geological features of the complex seismic wave field, summed up in the seismic wave propagation in the tunnel on the practical application of seismic reflection method to provide some theoretical guidance.This paper first introduces the Tunnel at home and abroad and seismic forecasting the status of numerical simulation and a variety of forecasting methods and their principles, advantages and disadvantages. Secondly, the theoretical basis of seismic waves and the finite element method based on doing a simple introduction. The third part of the wave simulation using Ricker source, to discuss the source of two-dimensional loading guns seized in the case of exchange of the difference between seismic wave field. Part IV to simulate the existence of the tunnel in front of the typical bad faults and karst geological field when the propagation of seismic waves to obtain the corresponding model at different time snapshots and synthetic seismic records, summarizes the tunnel propagation of seismic wave field, to deepen awareness of the tunnel snapshots for the tunnel to explain the inversion of reflected wave detection to provide theoretical guidance. Also discussed the issue on the resolution of seismic waves, through a variety of models of different sizes to verify the seismic waves on the vertical resolution of horizontal resolution and the theory of the first Fresnel zone deepened understanding of the theory. By extracting the tunnel snapshots and synthetic seismograms and seismic wave field separation of the tunnel in front of a variety of adverse geological characteristics of complex wave field permit discussion and analysis.