摘要
基于二维有限元数值方法，模拟复杂条件下隧道内的地震全波波场，分析隧道地震超前预报中反射记录的多方向和多波反射波特征，证实分离前方有效反射波和其他方向的干扰反射波，以及有效反射波的P波、S波分离在预报准确性中的重要性。基于多个数值模型，研究了F—K变换进行波场分离的有效性和影响因素。研究表明，在隧道前方反射层倾向与隧道轴线交角变化较大范围内（90°～45°），F—K变换都可以有效分离多方向和多波反射事件，提取主要来自掌子面前方的有效反射波剖面。来自隧道顶、底的缓倾界面的具有双曲时距曲线特征的干扰波和S波的高视速度会对P波的波场分离产生较大干扰；而由于S波的低速和强能量特征，其波场分离受具有双曲时距曲线特征的干扰波的视速度影响较小，且不受P波的影响。
The simulation of tunnel seismic wave field under complex conditions using the finite element meth- od was presented in the paper. The characteristic analysis of the multi-directions and multi-components of the reflec- tion records in tunnel indicate the importance of the separation of interested reflected seismic wave ahead of tunnel face from other directions and that of interested P-wave and S-wave. Based on several numerical models, the analysis of flexibility of the F-K conversion for the wave field separation show that F-K conversion is effective in the separa- tion of the multi-directions and multi-components of the reflection records from the wave ahead of tunnel face, even if the dips of reflector ahead of tunnel are varying widely （90° -45°）. Because of the effects of high apparent veloci- ty and interference waves, in the subsequent processing, P-wave has been separated as the main basis for S-wave profile. For the angle of reflection layer 〈 45°, due to its time-distance relationship is non-linear, the difference between the designed filter of apparent velocity which based on the linear relationship of the direct wave and actual relationship is too large for pressure or shear waves, therefore errors of separation are large, so adopted migration processing before the F-K conversion for the flat dipping fault.
出处
《大地测量与地球动力学》
CSCD
北大核心
2014年第4期71-76,82,共7页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金项目(40874051)
关键词
隧道地震超前预报
波场分离
F—K变换
数值模拟
双曲时距关系
tunnel geological prediction
wave separation
F-K transform
numerical simulation
hyperbolic time-distance relationship
