双江口电站超高应力区地下厂房岩爆空间特性规律研究

Study on spatial characteristics of rockburst in underground powerhouse of Shuangjiangkou Hydropower Station in ultra-high stress area

双江口电站左岸实测地应力达37.82MPa,从地应力平面空间展布规律和技施阶段岩体空间应力测试成果分析,地应力具有一定的区域差异性,可从洞室布置区域的地应力大小、洞轴线与地应力方向夹角关系宏观定性分析主副厂房岩爆最强、破坏现象最严重,上游侧岩爆破坏大于下游侧,数值模拟定量分析也得到相同结论。开挖后,在现场大量调查、统计岩爆发育基础上,对岩爆的空间特性进行了分析,概括总结了宏观岩爆空间发育规律,3大洞室中主副厂房岩爆最严重、尾调室次之、主变室最弱,主厂房岩爆破坏程度中导洞、第Ⅰ层、第Ⅱ层上游侧拱肩和边墙大于下游侧,而第Ⅲ层、第Ⅳ层下游侧岩锚梁和边墙大于上游侧岩锚梁和边墙,宏观调查规律与前期成果较吻合。结合微震监测事件空间分布规律,研究发现双江口电站具有典型的岩爆空间特性,通过总结这些特征,可初步预估小尺度区域岩爆特征,对今后引水系统地应力细化研究及支护具有一定的指导意义。

The measured ground stress on the left bank of Shuangjiangkou Hydropower Station reached 37.82MPa.From the analysis of the spatial distribution law of ground stress and the spatial stress test results of rock mass in the technical construction stage,the ground stress has certain regional differences.From the macro qualitative analysis of the magnitude of ground stress in the cavern layout area and the angle between the tunnel axis and the direction of ground stress,the rock burst of the main and auxiliary power houses is the strongest and the destruction phenomenon is the most serious,and the rock burst damage on the upstream side is greater than that on the downstream side,Numerical simulation and quantitative analysis also get the same conclusion.After excavation,based on a large number of on-site investigations and statistics on the development of rock burst,the spatial characteristics of rock burst were analyzed,and the macro spatial development law of rock burst was summarized.Among the three caverns,the rock burst in the main and auxiliary power houses was the most serious,followed by the tail dispatching room,and the main transformer room was the weakest.The damage degree of rock burst in the main power house was greater in the pilot tunnel,the spandrels and side walls on the upstream side of the first and second layers than that on the downstream side,while the third layer The rock anchor beam and side wall at the downstream side of the fourth layer are larger than those at the upstream side,and the macro investigation law is consistent with the previous results.Combined with the spatial distribution law of microseismic monitoring events,it is found that Shuangjiangkou Hydropower Station has typical spatial characteristics of rockburst.By summarizing these characteristics,the characteristics of small-scale regional rockburst can be preliminarily estimated,which has certain guiding significance for the refinement of ground stress and support of water diversion system in the future.