基于微震监测的川藏铁路某隧道岩爆预测研究

Research on the Rock Burst Prediction of a Tunnel in Sichuan-Tibet Railway Based on Microseismic Monitoring

研究目的:高地应力隧道岩爆成因和监测预警机制是长大深埋隧道施工与运营亟待解决的问题之一,微震监测作为岩体微破裂空间监测技术在隧道工程预警上发挥重要作用。本文以川藏铁路巴玉隧道为研究对象,采用IMS-16微震系统对隧道岩体破裂进行实时监测,基于微震监测预警原理,对微震监测关键技术与流程进行总结,建立基于隧道微震信息的岩爆预测评价机制,并采用现场试验验证岩爆预测评价结果。研究结论:(1)岩爆等级与微震能量、视体积、地震矩等震源参数有关;(2)根据微震监测系统预警区域内微震活动特征参数、微震事件空间分布状态、累积微震事件数和累积微震释放能的变化规律,综合微震监测数据及现场地质条件,可预测监测区域内岩爆等级且偏差不大;(3)预警区域微震事件呈空间聚集分布,累积微震事件数及累积微震释放能对数显著增长,说明该区域发生岩爆活动较活跃;预警区域微震事件呈空间分散分布,累积微震事件数及累积微震释放能无显著增长,说明该区域暂时无岩爆风险;(4)本研究结果可为岩爆微震监测提供科学依据,同时可为类似隧道的施工与管理提供参考借鉴。

Research purposes:The cause of rock burst and monitoring and early warning mechanism of high ground stress tunnel is one of the problems to be solved urgently in the construction and operation of long and deep buried tunnel.As a space monitoring technology of rock micro-fracture,microseismic monitoring plays an important role in the early warning of tunnel engineering.Taking Bayu tunnel of Sichuan-Tibet railway as the research object,IMS-16 microseismic system is used to monitor the rock mass fracture in real time.Based on the principle of microseismic monitoring and early warning,the key technologies and processes of microseismic monitoring are summarized,the rock burst prediction and evaluation mechanism based on the microseismic information of tunnel is established,and the field test is used to verify the prediction and evaluation results of rock burst.Research conclusions:(1)Rock burst grade is related to microseismic energy,apparent volume,seismic moment and other source parameters.(2)According to the characteristic parameters of microseismic activities,the spatial distribution of microseismic events,the number of cumulative microseismic events and the variation rules of the cumulative microseismic release energy in the early warning area of the microseismic monitoring system,the rock burst level in the monitoring area can be predicted with little deviation based on the microseismic monitoring data and field geological conditions.(3)The microseismic events in the early warning area are clustered and distributed in space.The cumulative number of microseismic events and the logarithm of cumulative microseismic released energy increase significantly,indicating that rock burst activities are relatively active in the area.The microseismic events in the warning area are distributed in space,and the cumulative microseismic events and the cumulative microseismic release energy have no significant increase,indicating that there is no rockburst risk in the area temporarily.(4)The research results can provide a scientific basis for rock burst microseismic monitoring,as well as a reference for similar tunnel construction and management.