【摘要】 基于隧道地震波场二维数值模拟是研究隧道超前探测过程中地震波传播规律的基础,目前关于这方面的研究均建立在隧道侧壁观测系统的基础上,并且把隧道空间作为与周围地层具有同样弹性参数的均匀介质考虑,因此不能实现全波场模拟,与实际存在差异。基于实际隧道空间,建立了更加接近实际的隧道地质模型,实现了隧道空间的二维全波场模拟。通过二维全波场模拟及实例结果对比分析表明:①采用空间四阶时间二阶交错网格有限差分法能有效实现基于隧道空气介质的二维全波场模拟;②当地质界面倾角为90°时,掌子面附近激发的共激发点观测系统比侧壁的共接收点观测系统更有利于反射波的获取;③随着地质界面倾角的减小,界面同侧激发和接收的反射波能量增强;④对于局部地质体和大倾角地质界面,掌子面附近激发横波能量强于纵波,有利于横波成像。更多还原

【Abstract】 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.更多还原