深埋TBM隧道施工微震监测规律
Microseismic characteristic analysis in deep TBM construction tunnels

随着各类地下工程向着深部发展，因开挖卸荷导致的围岩失稳问题日益突出。为了对围岩失稳进行预报预警，该文以西藏在建的某公路隧道为研究对象，构建了微震监测系统，总结了深埋隧道隧道掘进机（tunnel boring machine，TBM）开挖过程中微震活动的时空演化规律，揭示了微震事件b值与围岩失稳风险水平之间的关系。结果表明：微震事件数及其能量随TBM日掘进进尺的增大而增多；岩体垮塌发生前，微震事件在空间上聚集，时间上呈增多趋势，微震事件聚集区域与岩体垮塌位置吻合；微震事件b值能够表征隧道围岩稳定性。研究结果验证了微震监测技术用于洞室围岩稳定性评价的可行性，并为微震监测技术在类似工程中的应用提供了参考。
Abstract：The increasing depth of underground construction tunnels has led to instabilities of the surrounding rock caused by the excavation unloading is the rock structures. A real-time microseismic monitoring system was built to monitor and evaluate the stability of the rock during excavation foe a tunnel in Tibet, China. The system measured the temporal and spatial evolution of the microseismic activities during tunnel boring machine (TBM) excavation. The results were used to relate the b-values of the microseismic events and the stability risks of the surrounding rock. The results show that the number of microseismic events and the energy released increase with increasing TBM activity. A large number of microseismic events are concentrated in space and time before collapse of the rock mass and the gathering area coincides with the position of the rock mass collapse. The b-value is an important index to evaluate the surrounding rock stability. The results verify the feasibility of microseismic monitoring to evaluate the stability of the surrounding rock and a reference for microseismic monitoring in similar projects.