硐室围岩应力场对地倾斜观测影响的模拟分析  

Simulation Analysis of Influence of Stress Field in Surrounding Rocks of Chambers on Ground Tilt Observation

作　　者：武永彩[1] 唐红涛[2] WU Yongcai;TANG Hongtao(Xi'an Siyuan University ,Xi'an 710038. Shaanxi, China;The Second Monitoring and Application Center, CEA, Xi'an 710054, Shaanxi, China)

机构地区：[1]西安思源学院,陕西西安710038 [2]中国地震局第二监测中心,陕西西安710054

出　　处：《地震工程学报》2018年第1期146-152,共7页China Earthquake Engineering Journal

基　　金：中国地震局震情跟踪青年课题(2017010233)

摘　　要：在地震台观测仪器所在的地下硐室形成初期,由于硐室围岩为满足周壁法向应力为零的边界条件,底板会出现底鼓现象,其为一个缓慢过程,会严重影响地倾斜观测的长趋势变化,给地震监测工作带来误判。通过对硐室在地应力作用下的数值模拟,给出其围岩应力场分布特征,获取底板模型各网格点Z方向上的形变值,并将其换算为地倾斜数据。结果揭示,对地震观测仪水平摆产生影响的是硐底最大主应力场的变化;根据仪器在硐底的不同位置,会伴随不同程度的拉应力场变化,这种拉应力在竖直方向上不规则的梯度变化,导致硐底产生地表隆起现象,造成硐室内部地倾斜发生变化,其对地倾斜观测的影响范围在17.46~8 177.02/10^(-3″)。该结果有利于给新建硐室提供底板支护要求与依据,从而更好地服务于我国的防震减灾事业。In the early stages of underground chamber formation,where the earthquake observation in-struments are located,the chamber floor will exhibit the phenomenon of floor heave.Being a slow process,it will seriously affect the long time change of ground tilt observation,and thus cause misjudg-ment in earthquake monitoring.In this study,through the numerical simulation of an underground stress chamber,we propose a stress field distribution law in the surrounding rocks of the chamber,which is obtained in the Z direction deformation values of the grid nodes at the chamber floor.Then these deform-ation values are converted to tilt observation data.The results show that the change of the maximum principal stress field at the chamber floor will affect the horizontal pendulum of the seismograph.The tensile stress field varies at different degrees with different instrument positions.This irregular gradient tensile stress change in the vertical direction leads to the floor heave phenomenon,which results to the change of ground tilt in the chamber.The influence range of the ground tilt is between17.46and8177.02/103arc-seconds.This study can help in meeting floor support requirements and the basis for a newly-built chamber^in order to better serve earthquake research in China.

关 键 词：硐室 围岩压力 二次应力场 底鼓 地倾斜 

分 类 号：P315.6[天文地球—地震学]