地球物理学进展 ›› 2019, Vol. 34 ›› Issue (2): 817-825.doi: 10.6038/pg2019CC0025

• 应用地球物理学Ⅱ(海洋、工程、环境、仪器等) • 上一篇    下一篇

隧道反射地震超前预报波场分离方法的数值模拟研究

曾胜强1,3,刘争平2,奉建军2,肖薄2,黄云2,李京京2   

  1. 1. 西南交通大学地球科学与环境工程学院,成都 610000
    2. 西南交通大学土木工程学院,成都 610000
    3. 中铁四院集团广州设计院有限公司,广州 510600
  • 收稿日期:2018-07-21 修回日期:2019-01-17 出版日期:2019-04-20 发布日期:2019-05-13
  • 作者简介:曾胜强,男,1992年生,湖南宁乡人,西南交通大学硕士研究生,主要研究方向为隧道反射地震超前预报.(E-mail:675529649@qq.com)
  • 基金资助:
    国家自然科学基金项目"深埋长大隧道施工噪声震源波场实验和模拟研究"资助.(40874051)

Numerical simulation study the wave field separation method of tunnel reflection earthquake advance forecast

ZENG Sheng-qiang1,3,LIU Zheng-ping2,FENG Jian-jun2,XIAO Bo2,HUANG Yun2,LI Jing-jing2   

  1. 1. Southwest Jiaotong University School of Geosciences and Environmental Engineering, Chengdu 610000,China
    2. Southwest Jiaotong University School of Civil Engineering, Chengdu 610000,China
    3. Guangzhou Holding Company of the China Railway Siyuan Survey and Design Group Company Limited, Guangzhou 510600,China
  • Received:2018-07-21 Revised:2019-01-17 Online:2019-04-20 Published:2019-05-13

摘要:

本文以有限元数值模拟方法为依托,依次从波场快照、地震记录、波场分离、工程实例等四个角度论证了地震波传播规律和波场分离特点.模拟了单界面介质条件下地震波在隧道围岩中传播的全波波场.研究了反射波时距曲线的线性相关系数.比较了τ-p 变换和F-K变换的滤波特点.结合工程实例,讨论了这两类线性波场分离方法在提取隧道前方反射波中的可行性和准确性,研究结果表明:当隧道前方地层倾角由直立变为缓倾时,反射纵波和横波的时距关系都能很好的视为线性.地层倾角的改变主要影响反射波走时和视速度.因此,应用τ-p 变换和F-K变换进行波场分离,提取隧道前方单独的反射纵波和横波是可行和有效的.但对于缓倾地层,线性变换波场分离的结果存在较大的走时和视速度误差.易误滤除反射信号,需进行偏移处理.

关键词: 隧道地震超前预报, τ-p变换;, F-K变换, 有限元数值模拟, 波场分离

Abstract:

Based on FEM numerical method,this paper demonstrates the laws of seismic wave propagation and the characteristics of wave field separation from the four perspective which are wave field snapshots, earthquake records, wave field separation and engineering examples. The propagation features of seismic wave fields in the tunnel rock of a single reflector are simulated. The linear approximations of the time-distance relation of reflected waves are analyzed and the features of linear.τ-p and F-K transforms are also discussed. In combination with a engineering case, the feasibility and precision of the transform methods for the wave field separation which extracts the reflected waves from the ahead of tunnel excavation face are also analyzed. The research results show that the time-distance relations of the reflected P-waves and S-waves from the ahead of tunnel face with varying inclination angle can be well approximated with the linear relations because of the short observation layout for the tunnel seismic prediction. The change of the inclination angles of the reflectors mainly affect the arrival time and apparent velocity of the waves. Thus, it is feasible and effective for the separation of the reflected waves from the ahead of tunnel face by means of the linear τ-p and F-K transforms. In the stratum of low inclination angles, The two transform methods will cause the errors of arrival time and apparent velocity, which lead to filter the reflected signal.Therefore,there is needing offset processing.

Key words: Earthquake forecast ahead of the tunnel, τ-p transform;, F-K transform, FEM numerical, The wave field separation

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