隧道空间不良地质体地震波场响应特征研究

To improve the precision and accuracy of detecting the adverse geological structure and physical parameters of the seismic class tunnel geological prediction method,it is very important that we carry out the resecarch on the seismic wave field response features of the adverse geological bodies in the tunnel space that is closely related to the basic theory of this method..The topic is based on the non-uniform viscoelastic medium approximation of the actual tunnel rock mass constitutive model，and derive the absorption and attenuation characteristics of the seismic wave in the tunnel rock by carrying out seismic wave propagation in viscoelastic media theory . For the tunnel space small venues and confounding factors, we design the whole space observing systems, and establish the theoretical model of the major adverse geological bodies encountered in the tunnel construction including the fracture zone, the karst aquifer body and the different inclination of the second floor media and the three-media interface. Case to consider the medium of the air inside the tunnel, we obtain the seismic wave field records of the adverse geological bodies of the tunnel space by order staggered grid finite difference method, and study the response characteristics of the wave field. The research results provide a theoretical basis for the optimal placement of the seismic class observing systems, data acquisition and detailed interpretation in the advanced geological prediction method, and the research results in engineering practice have very important theoretical significance and practical value for protecting the tunnel construction safety, and promoting the development of the seimic class tunnel advanced geological prediction method.

为提高地震类隧道超前地质预报方法探测不良地质体结构和物性参数的精度和准确性，开展与该方法基础理论密切相关的隧道空间不良地质体地震波场响应特征研究十分重要。.本课题以更逼近实际隧道岩体的非均匀粘弹性介质本构模型为基础，通过开展粘弹性介质中地震波传播理论研究，获得隧道岩体中地震波吸收和衰减特性；针对隧道空间场地狭小，干扰因素多的特点设计全空间观测系统，建立断层破碎带、含水岩溶体、不同倾角二层介质和三层介质分界面等隧道施工中常见不良地质体的理论模型；在考虑隧道内空气介质的情况下，通过高阶交错网格有限差分数值模拟方法，获得上述不良地质体的隧道空间地震波场记录，研究其波场响应特征，为地震类超前地质预报方法的观测系统优化布置、数据采集与精细解释提供理论依据，将研究成果应用于工程实践，对保障隧道施工安全，推动地震类隧道超前地质预报方法的发展具有重要的理论意义和实际应用价值。

隧道地震超前地质预报结果的准确性和精度与隧道不良地质体的波场特征密切相关，相关研究主要以在隧道侧壁上建立的观测系统为基础，同时把隧道空间作为均匀介质考虑，其弹性参数与周围岩体相同，无法进行全波场模拟，与隧道实际情况有较大差别。.本课题的主要研究内容包括非均匀粘弹性介质中地震波吸收、衰减特性研究；非均匀粘弹性介质中地震波波场数值模拟研究；隧道空间不良地质体地震波场响应特征研究。.研究取得的主要结果、关键参数及其科学意义包括：.（1）把隧道作为空气介质建立地质模型，并加入吸收边界条件，采用空间四阶时间二阶交错网格有限差分法，可有效、正确地实现隧道空间的二维地震全波场模拟；波场特征能够正确反映不同地质体下地震波的传播形态以及变化规律，可以为实际隧道超前预报观测系统的设计和数据的采集提供依据，同时也为隧道地震超前预报成像及反演研究提供了基础。.（2）当地质界面倾角为90°时，在隧道两侧壁激发和接收时获得的反射波能量较弱，因此在掌子面上或附近激发，采用共激发点观测系统有利于反射信息的获得和界面的成像。.（3）随着地质界面倾角的逐渐减小，在隧道中靠近地质界面一侧激发时，同侧接收的反射波能量逐渐增强，侧壁观测系统有利于反射波的获取。.（4）对于溶洞和大倾角地质界面，在掌子面和附近激发时，采用共激发点观测系统可获取较强的横波反射能量，有利于横波勘探。