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.
出处
《哈尔滨工程大学学报》
EI
CAS
CSCD
北大核心
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)
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
microseismic monitoring
microseismic activity
rock damage
crack propagation
rockburst
deep-bur- ied tunnel
