Excavation-induced microseismicity: microseismic monitoring and numerical simulation
Excavation-induced microseismicity: microseismic monitoring and numerical simulation
复制标题
开挖引发的微震活动：微震监测和数值模拟
DOI：
10.1631/jzus.a1100131
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发表时间：
2012-06-01
影响因子：
3.2
通讯作者：
Wu, Ji-chang
中科院分区：
文献类型：
--
作者：
Xu, Nu-wen;Tang, Chun-an;Wu, Ji-chang
大岗山水电站右岸边坡开挖影响量主要是通过微震监测、数值模拟和常规测量以及现场观测确定的。微震监测是研究岩质边坡微裂缝的新应用技术。自2010年5月起，系统利用微震监测网对岩质边坡连续开挖引起的岩体卸荷松弛和后期大坝蓄水引起的应力重分布进行监测，识别并圈定了潜在滑移区。有了一个重要的地震震源位置数据库。微震事件分析显示出特定的时空分布。地震事件主要发生在海拔1180 m的上游斜坡附近，尤其集中在XL316-1断层的上盘。采用RFPA-SRM代码（现实失效过程分析-强度折减法）对这种现象进行数值模拟。通过将微震活动及数值模拟结果与现场观测和常规测量结果进行对比，发现震源位置与工作区内开挖应力分布具有较强的相关性。由此确定了岩质边坡的影响体积。工程实践表明，微震监测能够准确诊断断层、卸荷带等构造活动的震级、烈度及其时空特征。采用地震监测与数值模拟相结合、现场观测与常规测量相结合的综合技术，从不同角度更好地认识右岸边坡微震活动与应力场的内在作用及相互关系。
The volume of influence of excavation at the right bank slope of Dagangshan Hydropower Station, southwest China, is essentially determined from microseismic monitoring, numerical modeling and conventional measurements as well as in situ observations. Microseismic monitoring is a new application technique for investigating microcrackings in rock slopes. A microseismic monitoring network has been systematically used to monitor rock masses unloading relaxation due to continuous excavation of rock slope and stress redistribution caused by dam impoundment later on, and to identify and delineate the potential slippage regions since May, 2010. An important database of seismic source locations is available. The analysis of microseismic events showed a particular tempo-spatial distribution. Seismic events predominantly occurred around the upstream slope of 1180 m elevation, especially focusing on the hanging wall of fault XL316-1. Such phenomenon was interpreted by numerical modeling using RFPA-SRM code (realistic failure process analysis-strength reduction method). By comparing microseismic activity and results of numerical simulation with in site observation and conventional measurements results, a strong correlation can be obtained between seismic source locations and excavation-induced stress distribution in the working areas. The volume of influence of the rock slope is thus determined. Engineering practices show microseismic monitoring can accurately diagnose magnitude, intensity and associated tempo-spatial characteristics of tectonic activities such as faults and unloading zones. The integrated technique combining seismic monitoring with numerical modeling, as well as in site observation and conventional surveying, leads to a better understanding of the internal effect and relationship between microseismic activity and stress field in the right bank slope from different perspectives.