以西藏多雄拉隧道作为研究对象,在隧道施工过程中构建微震监测系统,对TBM(Tunnel boring machine)掘进过程中微震信号的规律以及岩爆发生前微震信号的演化过程进行研究。结果表明:(1)微震事件总体上随着掘进进尺速率的增加而增加;(2)TBM开挖过程中围岩应力调整危险区域主要在掌子面前方1D和掌子面后方3D范围内,这与岩爆发生的区域一致;(3)矩震级大于零的微震事件可以作为岩爆预警的信号,同时注意强岩爆发生后次生灾害的防护;(4)能量指数的下降和累计视体积的上升可以作为岩爆发生前的预警信号。
Taking the Duoxiongla Tunnel in Tibet as the engineering background, a microseismic monitoring system was constructed. The law of microseismic signals during TBM excavation and the evolution process of microseismic signals before rockbursts are studied. The research results show that (1) microseismic events generally increase with the increase of excavation footage. (2) During TBM excavation, the danger zone of surrounding rock stress adjustment is mainly in the range of 1D in front of the face and 3D behind the face, which is consistent with the area where rockburst occurs. (3) Microseismic events with moment magnitude greater than 0 can be used as rockburst early warning signals, and at the same time, attention should be paid to the protection of secondary disasters after strong rockbursts occur. (4) The decrease of energy index and the increase of cumulative apparent volume can be used as early warning signals before rockburst.
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