| In recent years, a large number of the tunnel projects have appeared with the rapid development of road, rail and other construction projects in our country. Since the geology circumstance in front of the digging face is unknown, it often causes engineering accidents because of meeting geological hazard in the process of tunnel construction. Therefore, tunnel advanced prediction is very important in tunnel projects. Seismic wave reflection method is currently one of the most widely used methods and has accumulated many successful experiences in tunnel engineering. However, there are some problems such as discrimination depend on experience, lower positioning accuracy. This paper apply dynamic finite element analysis software to simulate the propagation and reflection of seismic wave in the tunnel rock system according to the research status of seismic wave reflection method at home and abroad, and study the waveforms indifferent conditions. The main contents and conclusions in this paper are as follows:(1) This paper expounds the theoretical basis of seismic wave reflection method the seismic prediction method advanced prediction, as well as the algorithm principle of dynamic finite element method, and provide a reliable theoretical foundation and technical support for numerical simulation of seismic wave.(2) Layered system finite element model was established and the feasibility of using dynamic finite element method to simulate seismic wave was verified, and provides the basis for further analysis of the complex working condition.(3) Three-dimensional finite element model of the tunnel was established, receiving points were set in different locations of the tunnel to study the effect of different observing ways on the reflection waveform, and the effect of the working face on the reflection waveform has been obtained.(4) Unfavorable geological bodies of different distance, different sizes were set in front of the working face to study the reflection waveform, and the effective detection distance and accuracy has been obtained primarily in theory.(5) The lithology parameters of the setting rock in front of working face were changed to study the reflection waveform, the effect of the change of density, Poisson's ratio, elastic modulus on the reflection waveform has been obtained.This paper applies dynamic finite element analysis software to simulate the propagation and reflection of seismic wave. The analysis of the forward results of various unfavorable geological bodies is to deepen the understanding of the seismic reflection profiles, accumulate the discriminant experience of geological structures based seismic reflection images, and improve seismic interpretation accuracy. The correctness of inversion algorithm can be verified by using the forward results of the known model to inverse, provide a useful reference to the development and improvement of inversion software. |
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