局部能量释放率与微震相结合的岩爆动态预警指标

基于锦屏二级水电站引水隧洞、排水洞施工过程中的大量的微震信息以及不同等级的岩爆实例,运用数值计算与微震信息相结合的手段的对岩爆灾害进行研究。结果表明,局部能量释放率可以作为高地应力条件下隧洞开挖过程中围岩能量释放的指标,将其与微震监测数据相结合可以对深埋隧洞开挖过程中岩爆的强度、发生位置及范围进行预警:当局部能量释放率指标达到4×10⁵ J/m³以上,同时最大能量微震事件的能量值大于10⁵ J时,将发生强烈岩爆;当局部能量释放率指标介于10⁵~4×10⁵ J/m³之间,最大微震能量值在10⁴~10⁵ J之间时,具有中等或轻微岩爆风险;当局部能量释放率低于10⁵ J/m³,微震能量均值小于10⁴ J时,无岩爆风险。最后在施工过程中对上述预警指标进行运用,有效的抑制了岩爆灾害的发生。

Dynamic Warning Index of Rockburst Based on Local Energy Release Rate and Microseismic Informations

Based on a large amount of microseismic informations and hundreds of rockbursts occurred in four deep headrace tunnels and the one water drainage tunnel at Jinping II hydropower station in Sichuan province, China. Numerical calculation was combined with micro-seismic monitoring in order to research the evolution processes of rockbursts. The achieved results are as follows: Local energy release rate (LERR) was used as an indexes of energy release in deep tunnel excavation, which was combined with seismic informations, the intension and position of rockburst and the extent of brittle failure zone can be analyzed quantitatively. When Local energy release rate (LERR) was >4×10⁵ J/m³and the common logarithms of the maximum micro-seismic energy was >5, have the risk of intense rockbursts. LERR was >10⁵ J/m³ and <4×10⁵ J/m³, the common logarithms of the maximum micro-seismic energy was >4 and <5, weak or moderate rockbursts was happened. LERR was <4 and the common logarithms of the maximum micro-seismic energy was <4, there would be no rockburst. The result can provide reasonable and scientific basis that prediction and prevention rockbursts during tunnels rockmass excavation under high geostress.