Abstract:
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.