高地应力区地下厂房开挖中微震活动性分析

Analysis of microseismicity in excavation of underground powerhouse in high geo-stress area

猴子岩水电站地下厂房埋深大、地应力高,厂区地质条件复杂,发育多组结构面和次级断层。为研究地下厂房围岩在开挖过程中的稳定性,采用加拿大ESG微震监测系统进行了实时动态监测。监测数据显示,地下厂房围岩开挖过程中微震事件数量偏多,主要聚集在1号与3号母线洞之间及其上部围岩;同时,结合施工情况和地质条件分析,该区域为识别和圈定的潜在失稳破坏区域。在已有微震资料基础上,借助常规监测数据,解释了围岩变形与微震空间分布之间的内在联系。研究结果可以为地下厂房支护措施提供参考,也为更好地理解和探索高应力岩体损伤变形机制予以借鉴。

The underground powerhouse of Houziyan Hydropower Station is characterized as large buried depth, high geo-stress and complicated geological conditions, developed structural planes and secondary faults. In order to study the stability of surrounding rock of underground powerhouse during the excavation, the real-time dynamic monitoring was carried out by using ESG Microseismic Monitoring System of Canada. The monitoring results showed that the number of micro-seismic events during excavation was relatively large and concentrated between No. 1 and No. 3 busbar tunnels and the upper surrounding rock. Mean-while, through the analysis of construction situation and geological condition, this area was recognized and marked as unstable ar-ea. On the basis of existed microseismicity data, by using conventional monitoring data, the inner relationship between deforma-tion of surrounding rock and spatial distribution of microseismicity was explained. The research results can provide reference for subsequent support construction, also help understanding the rock damage and deformation mechanism under high geo-stress sit-uation.