深埋TBM隧洞岩爆事件微震释放能及等级认定——以Neelum-Jhelum水电工程为例

Microseismic energy and intensity criterion of rockburst in deep TBM tunnels:A case study of the Neelum-Jhelum hydropower project

深埋全断面隧道掘进机(TBM)开挖诱发的岩爆灾害严重危害施工安全,开展TBM隧洞岩爆研究具有重要意义。基于巴基斯坦Neelum-Jhelum水电站深埋TBM隧洞的43个岩爆案例及原位微震实时监测信息,对TBM隧洞岩爆事件发生时刻的微震释放能及岩爆等级认定标准进行了研究。采用距离判别法对岩爆事件进行预处理以扩充岩爆案例,研究了不同等级不同岩性条件下TBM隧洞岩爆事件的微震释放能特征。利用微震释放能定量参数,建立了不同条件下微震释放能TBM隧洞岩爆等级的认定标准。岩爆等级越高,微震释放能的定量阈值越大,两者呈现非线性关系;相同等级岩爆,砂岩的阈值要高于粉砂岩。因此,在对岩爆事件的等级进行认定时,有必要区分岩性。基于工程实例对所建立的认定标准进行验证分析,证明所建立的认定标准可用可靠。该研究成果可为深埋TBM隧洞岩爆认知和预警提供依据。

Rockburst hazards caused by excavation in deep tunnel boring machine(TBM)tunnels endanger construction safety.Based on 43 rockburst events and related microseismic(MS)energies in the deep TBM tunnels in the NeelumJhelum hydropower station in Pakistan,the MS energy characteristics and intensity identification of rockburst events in deep TBM tunnels were studied.The rockburst event was preprocossed using distance discrimination method for case expansion,and the characteristics of MS energies of rockburst events with different intensities and lithological conditions in TBM tunnel were investigated.Using the quantitative parameter of MS energy,a criterion for identifying the rockburst intensity in deep TBM tunnels under different conditions was established.The higher the rockburst intensity,the greater the quantitative threshold of MS energy,and the two show a nonlinear relationship.The threshold value of MS energy for sandstone is greater than that of siltstone for the same intensity of rockburst.It is necessary to differentiate the lithology when identifying the intensity of rockburst events.The established criterion was validated in the project,and the results show that the established criterion is reliable.The results can provide a basis for understanding rockburst events and provide advance warning thereof in deep TBM tunnels.