ABSTRACT

Based on a series of laboratory tests and in situ monitoring and tests at deep tunnels excavated by TBM or D&B method, mechanism of evolution process of different types of rockburst, including strain burst, strain-structure slip rockburst, immediate rockburst and time delayed rockburst, and has been understood. The digital borehole televiewer and seismicity monitoring system have been used to obverse cracking initiation and propagation process during rock burst evolution process. A warning system based on micro seismicity has been established for warning of various intensities of rockbursts, such as slight, moderate, intensive and extremely intensive rockbursts. The probability with the intensity of rockburst is also given. The strategy for excavation and support design has been recommended for various intensities of rokcburst before the excavation. The strategy for dynamic control of rockburst evolution process is also proposed according the warning. The methodology has been successfully applied to rockburst risk reduction for deep tunnels at Jinping II hydropower station. The results have illustrated applicability of the proposed methodology and techniques on rockburst.

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