Research on Microseismic Event Law of Deep Buried Tunnel and Microseismic Information of Rock Burst Precursor

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.