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以锦屏二级水电站TBM开挖的深埋隧洞为工程背景,基于微震监测数据和岩爆实例,研究了深埋隧洞TBM掘进过程中微震与岩爆时空分布特征及岩爆孕育过程微震演化规律。结果表明:(1)微震活跃期和岩爆高发期处于TBM作业时段及停机后的1 h以内;微震活动范围主要介于掌子面后方3倍洞径至前方0.4倍洞径之间,其峰值位于掌子面后方0.8倍洞径附近;而岩爆主要发生在掌子面后方2倍洞径以内,尤其是掌子面后方1倍洞径以内是岩爆高发区;可见,微震与岩爆具有良好的时空相关性。(2)在时间序列上,微震能突增现象,以及累积视体积快速上升而Schmidt数急剧下降的现象均属微震活动异常,属岩爆前兆。(3)在空间序列上,微震事件逐渐向某个区域高度集结且大震级高能量事件不断增多的现象属微震活动异常,预示高岩爆风险,属岩爆前兆。
Based on the microseismic monitoring data and rock burst examples, the spatial and temporal distribution of microseismicity and rockburst and the microseismic evolution of rockburst during the TBM tunneling process are studied based on the TBM excavation of Jinping II Hydropower Station. . The results show that: (1) the period of microseismic activity and rock burst is within 1 h of TBM operation and shutdown; the range of microseismic activity is mainly between 3 times the diameter of the back of the face and 0.4 times of the diameter of the front And the peak value is 0.8 times behind the face of the face. The rockburst mainly occurs within 2 times of the back of the face, especially within 1 time of the back of the face. It can be seen that the microseismic and rock Explosion has good spatiotemporal relevance. (2) On the time series, the phenomena of sudden increase of microseismic energy and the rapid increase of cumulative apparent volume and the sharp decrease of Schmidt number belong to microseismic anomalies, which are precursors of rock burst. (3) In the spatial sequence, the phenomenon that microseismic event is highly concentrated to a certain area and the large-scale high-energy event is increasing is a microseismic activity anomaly, which indicates that the risk of high rock burst is a precursor of rock burst.