反射波法隧道超前地质预报地震波走时模拟研究

STUDY ON SIMULATION OF SEISMIC WAVE TRAVEL TIME IN TUNNEL ADVANCED GEOLOGICAL PREDICTION USING REFLECTION WAVE METHOD

隧道施工安全常常由于复杂的地质情况面临着巨大的挑战,反射波法地震勘探具有探测深度大、抗干扰能力强等优点,是确保隧道施工安全的重要超前地质预报手段。反射地震波走时计算与地震数据处理中的纵横波分离、速度建模、偏移成像等多个步骤息息相关,直接影响着隧道地质预报的结果。本文将仿照反射波法隧道超前地质预报的实际施工区域进行速度建模,以求解程函方程为基础,结合快速推进法(FMM)中的迎风有限差分方法以及窄带扩展技术实现针对隧道模型的初至地震波走时模拟。并通过对隧道模型中反射界面位置信息的提取,构建反射波初始窄带以及结合窄带扩展技术实现针对隧道模型反射波走时的计算。通过数值分析以及复杂隧道模型计算表明,文中给出的反射波法隧道超前地质预报地震波走时模拟具有良好的计算精度以及较强的适应能力。

Tunnel construction safety often faces enormous challenges due to complex geological conditions.Reflection wave seismic exploration has the advantages of a large detection depth and strong anti-interference ability,making it an important advanced geological prediction method to ensure tunnel construction safety.The calculation of reflected seismic wave travel time is closely related to multiple steps in seismic data processing,such as the separation of longitudinal and transverse waves,velocity modeling,and migration imaging,which directly affect the results of tunnel geological prediction.This article will simulate the actual construction area of advanced geological prediction for tunnels using the reflected wave method for velocity modeling.Based on solving the functional equation,combined with the upwind finite difference method and narrowband expansion technology in the Fast Moving Method(FMM),the first break seismic wave travel time simulation for the tunnel model will be achieved.By extracting the location information of the reflection interface in the tunnel model,an initial narrow band of the reflection wave is constructed,and,combined with narrowband expansion technology,the calculation of the travel time of the reflection wave in the tunnel model is achieved.Through numerical analysis and complex tunnel model calculations,it is shown that the reflected wave method proposed in the article has good computational accuracy and strong adaptability in predicting seismic wave travel time in the advanced geological prediction of tunnels.