Two-dimensional numerical simulation of tunnel-based seismic full-wave fields
Two-dimensional numerical simulation of tunnel-based seismic full-wave fields
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发表时间：
2012
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通讯作者：
C. Jin
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作者：
C. Jin
基于隧道的二维地震波场数值模拟是隧道超前预报中分析地震波传播规律的基础，目前的研究都是在隧道侧壁设置观测系统，将隧道视为均匀介质，与周围介质的弹性参数相同，建立了更适合实际隧道的地质隧道模型，实现了地震全波场的二维数值模拟。（1）采用时间上具有二阶精度、空间上具有四阶精度的交错网格有限差分（FD）算法，可以在不忽略隧道空气介质的情况下实现地震全波场的二维数值模拟;（2）考虑垂直地质界面时，近掌子面共源系统比侧壁共源系统更有利于获得反射波;（3）当炮点和接收点在同一侧时，随着地质界面倾角的减小，反射波能量增加;（4）对于局部地质特征和界面，掌子面横波激发比压力波激发获得更多的能量，有助于横波成像。
The two-dimensional(2D) numerical simulation of seismic wave fields based on tunnels is a basis for the analysis of propagation laws of seismic waves in the tunnel prediction.All of the current researches,which are designed with observation systems on the sidewalls of tunnels and assume tunnels as homogeneous media with the same elastic parameters of surrounding media,are not in conformity with the actual situations because they cannot involve surface waves.A geological tunnel-based model is established,which is more suitable for the practical tunnels to achieve the 2D numerical simulation of seismic full-wave fields.The results show:(1) using a staggered grid finite-difference(FD) algorithm with a second-order accuracy in time and a fourth-order accuracy in space,we can achieve the 2D numerical simulation of seismic full-wave fields without ignoring the air medium in tunnels;(2) when considering a vertical geological interface,common-source system with shots near the tunnel face is better for obtaining reflection waves than the one with shots on the side walls;(3) with the decrease of the dips of geological interfaces,the energy of reflection waves increases when shots and receivers are on the same side;(4) for the local geological features and interfaces,shear wave shot on the tunnel face,which acquires more energy than pressure wave shot,can help in shear wave imaging.