地下洞室群开挖卸荷过程微震活动特征研究  

Characteristics of Microseismicity of Underground Group Caverns Subjected with Excavation Unloading

作　　者：沙椿[1,2] 李彪[3,4] 徐奴文[3,4] 戴峰[3,4] 何刚[2] 雷英成[2] 

机构地区：[1]中国电建集团成都勘测设计研究院有限公司,成都610072 [2]四川中水成勘院工程勘察有限责任公司,成都610072 [3]四川大学水利水电学院,成都610065 [4]四川大学水力学与山区河流开发保护国家重点实验室,成都610065

出　　处：《长江科学院院报》2014年第11期102-107,共6页Journal of Changjiang River Scientific Research Institute

基　　金：国家自然科学基金资助项目(51209127;51374149);国家重大基础研究计划973项目(2014CB047100);中国博士后科学基金资助项目(201M540549)

摘　　要：猴子岩水电站地下厂房开挖跨度大,其上覆岩体构造和受力条件复杂,开挖卸荷过程围岩稳定一直都是贯穿工程始终的重点和难点问题。目前常规监测手段难以对地下厂房围岩内部可能存在的微破裂进行有效监测和揭示,为实时分析开挖过程地下洞室群围岩变形和稳定性,2013年4月在猴子岩水电站地下厂房安装了高精度微震监测系统,实现了开挖卸荷过程地下工程深部围岩微破裂实时定位和分析。监测结果表明:微震活动性时空演化规律可以很好地揭示地下厂房岩体内部微破裂萌生、发育、扩展、相互作用和贯通直至宏观变形机制;同时,微震监测可以随厂房开挖工况动态识别和圈定围岩微破裂集中区域及其潜在变形失稳风险区域。最后,借助物探检测声波测试成果,建立微震活动性与岩体质量之间的联系。研究结果可供猴子岩水电站地下厂房下阶段开挖与支护参考和借鉴,也为类似深埋地下工程围岩稳定性预测和评价开辟了一条新的思路。The underground powerhouse of Houziyan hydropower station is a typical deep-buried powerhouse with characteristics such as large scale excavation span,complex structures and stress condition of overlying rock mass.The stability of rock mass in the process of excavation unloading has always been one of the most important and difficult problems during the project construction.So far conventional monitoring methods such as GPS,multiple position extensometers cannot effectively measure and reveal the microfractures inside the surrounding rock mass of underground powerhouse.A high resolution microseismic monitoring system was installed in the underground powerhouse on April 2013,aiming to real-time analyze the deformation and stability of surrounding rock mass subjected with continuous excavation.The real time positioning and investigation of microfractures in deep rock mass is achieved.The monitoring results show that the temporal-spatial evolution distribution regularity of microseismicity can demonstrate the failure mechanism of initiation,propagation,coalescence,interaction and breakthrough till macroscopic deformation of microcracks in deep rock mass of underground powerhouse.Meanwhile,microseismic monitoring can dynamically identify and delineate micro-fracture clustering areas of surrounding rockmass and the potential instability risk areas in the underground powerhouse along with continuous excavation.Finally,assisted with acoustic detection results,a relationship is established between microseismic clusters and rock mass quality.The results could provide guidelines for later excavations and supports in the underground powerhouse of Houziyan hydropower station.Moreover,it＇ s also a new idea for the stability evaluation of surrounding rock mass in similar deep-buried underground engineering.

关 键 词：微震监测 地下洞室群 开挖卸荷 损伤区 波速 

分 类 号：TV731.6[水利工程—水利水电工程] TV221.2