深埋硬岩隧洞微震监测及微震活动特征分析  

Monitoring and characteristic analysis of microseismic activities in deep hard-rock tunnels

作　　者：于群[1] 唐春安[1] 李连崇[1] 马天辉[1] 唐烈先[2] 

机构地区：[1]大连理工大学岩石破裂与失稳研究所,辽宁大连116024 [2]辽宁科技大学矿业工程学院,辽宁鞍山114051

出　　处：《哈尔滨工程大学学报》2015年第11期1465-1470,共6页Journal of Harbin Engineering University

基　　金：国家973计划资助项目(2014CB047100);国家自然科学基金资助项目(51174039;51279024);国家自然科学基金委创新研究群体基金资助项目(51121005)

摘　　要：针对高地应力和高埋深带来的深埋隧洞岩爆问题,以锦屏二级水电站深部引水洞为研究对象,对全断面隧道掘进机(TBM)开挖过程进行微震实时监测。结合微震活动时空强序列分布、微震事件密度及微震能量密度,总结微震活动的时空演化特征,并对地下硐室岩体强度损伤区进行圈定,进而识别发生岩爆的潜在危险区。监测与分析结果表明:多数岩爆都存在有可被微震监测定位的微破裂前兆,微震活动的活跃区和簇集区与岩爆位置具有空间一致性,在时间上的排序优先于岩爆事件。岩爆的发展及破坏过程是由岩体的浅表,经微裂纹的萌生、发展、扩展至岩体深部后形成宏观剪切裂纹,相邻的宏观剪切裂纹相互搭接后与隧洞壁形成三角形闭环。当岩体达到或者超过峰值强度时,岩爆发生。借助于震源理论,利用微震事件b值变化特征可对隧洞岩爆情况进行预测预警。Highly geostressed deep tunnel induced rockbursts were studied at the Jinping Ⅱ Hydropower Station. A real-time microseismic monitoring system was established to monitor the diversion tunnels during tunnel boring ma- chine （TBM） excavation. The distribution of microseismic events was recorded by time, location, magnitude, event density, and energy density, then summarized to show the evolution microseismic activity in space-time. Thus de- lineating rock damage zones in the underground tunnel, and identifying potentially dangerous rockburst zones. The monitoring results show that： most rockbursts have micro-fracture precursors, there is a spatial match between con- centrated active microseismic areas and rockburst areas, and microseismic sequences develop before rockbursts. Rockburst development and damage processes, including micro-crack initiation, development, propagation, and macroscopic shear crack formation, were experienced from the tunnel surface to deep inside the rockmass. A trigo- nal closed stress loop consisted of two overlapping shear cracks at the tunnel surface. When the stress exceeds rock peak strength, a rockburst will be triggered. In view of seismic theory, roekbursts may be predicted through varia- tions in b values generated by microseismic events.

关 键 词：微震监测 微震活动 岩体损伤 裂纹扩展 岩爆 深埋隧洞 

分 类 号：TU45[建筑科学—岩土工程]