锦屏一级水电站左岸边坡微震监测系统及其工程应用

锦屏一级水电站坝区山高坡陡,两岸山体地应力高,左岸存在深部裂缝、低波速松弛岩体、煌斑岩脉(X)及f2,f5断层等复杂地质条件。为对左岸边坡深部岩体微震活动性进行实时监测和分析,2009年6月该边坡安装加拿大ESG公司生产的微震监测系统。通过构建左岸边坡三维地质模型和优化传感器布设方案,采用人工定点爆破试验对监测系统定位性能进行测试,结果显示在传感器阵列范围内的震源定位误差小于12m,证明系统具有较高的定位精度。对拾取的事件波形进行分析和聚类研究,给出系统运行以来微震事件的时空分布规律,初步圈定左岸边坡微震活动引起的深部岩体变形区域,并结合RFPA有限元软件对比研究边坡应力场和潜在滑裂面。研究结果表明,该边坡微震监测系统的设计和实施满足深部岩体变形的全局监测,能够识别左岸边坡可能存在的潜在岩体破坏区域和滑移面,为边坡后期生产性灌浆以及加固处理提供一些参考,也为高岩质边坡稳定性分析提供一个新的研究思路。

MICROSEISMIC MONITORING SYSTEM ESTABLISHMENT AND ITS ENGINEERING APPLICATIONS TO LEFT BANK SLOPE OF JINPING I HYDROPOWER STATION

Many deep cracks and faults，such as f2，f5 and lamprophyres，which may result in huge potential instable blocks，are the most significant factors that influence the stability of the left bank slope of Jinping I Hydropower Station. In order to real-time monitor and analyze microseismicity in deep rock mass of the left slope，an ESG microseismic monitoring system manufactured in Canada was installed in June，2009. It is the first time to introduce microseismic monitoring technique into high steep rock slope engineering in China. On the basis of setting up three-dimensional geological model of the left slope and optimizing the sensor emplacement，the positioning accuracy of the system has been adjusted according to artificial fixed blasting tests. The results show that seismic source location error is less than 12 m in the scope of the sensor array，which demonstrates microseismic monitoring system has a high positioning accuracy. The waveforms analysis and clustering are investigated and different types of waveforms have been distinguished. Moreover，the tempo-spatial distribution regularities of microseismic events are also analyzed. In addition，a preliminary delineation of deep rock mass deformation zone induced by microseismicity in left bank slope is provided. Furthermore，the stress field and potential slip surface of left slope are simulated by RFPA，which is corresponding to the results of site exploration and microseismic monitoring. This research indicates that the design and implementation of microseismic monitoring system can meet the global monitoring of deep rock mass deformation，which could identify the potential rock damage regions and sliding surface. It will provide a reference for grouting and reinforcement of the left bank slope. A new idea on stability analysis of high rock slopes can thus be obtained.