岩体隧洞岩爆过程微震特征及其扩展机制

基于深部岩体隧洞不同开挖方式下的岩爆现场情况及微震监测数据，确立了最大能量微震事件岩爆发生时间、等级的判定标准。在此基础上，对深埋隧洞即时型岩爆的孕育及发生过程进行了研究，结果表明:即时型岩爆孕育过程中围岩岩体处于破坏加速集聚并不断扩展的过程，此过程中微震事件数量不断增加、能量参数不断增大，当岩爆发生时达到最大值；TBM开挖过程可近似为准静态卸荷，受到开挖方式的影响其裂隙扩展范围相对较小，围岩承载力也较强；而钻爆法开挖是初始应力的动态卸荷，爆破冲击荷载造成的裂隙扩展范围较大，同时其围岩储能能力相对较差。

Characteristics and evolution mechanism of micro-seismic events of rockbursts in deep rock tunnels

The micro-seismic monitoring data obtained from the rockbursts in the deep rock tunnels excavated by the drill-and-blast and tunnel boring machine (TBM) methods are analysed, and the analysis results concerning the daily maximum micro-seismic energy can be used as a basis for estimating the time and intensity of the rockbursts. The processes of immediate rockbursts with different excavation methods are compared, and the distribution characteristics of the micro-seismic imformations are analyzed. The analysis results show that the damage of the rock mass is gathering and expanding in the processes of the immediate rockbursts, and that the number and energy release of the micro-seismic events increase continuously before the rockburst happens and totally increase to a critical value when the rockburst happens: the TBM excavation involves a quasi-static unloading whose damage is to the local area, the bearing capacity and the storage capacity of the energy of the surrounding rock are stronger; and an initial in-situ stress of the tunnel face during TBM excavation consists of the dynamic unloading stress fields whose damage range is more wide, and the bearing capacity and the storage capacity of the energy of the surrounding rock are relatively poor. The analysis results not only help to understand the law of each rockburst, but also provide a reasonable scientific basis for prediction and prevention of the rockbursts in the deep rock tunnels under different excavation conditions.