Rock-burst and Its Countermeasure of TBM Construction in Drainage Tunnel of a Hydropower station

It had only been tunneled 1 027 m in previous 101 d in construction drainage tunnel of the Jinping Second cascade hydropower state. It had occurred 3 times rock-burst altogether in this period which immediately influence the tunneling process. The harm degree and the influence area of these rock-burst according to the time sequence which rock-burst occurred are discribed. The occurrence of rock-burst has certain regularity, which is not only related to high in-situ stress,but also related to the structural features of rock mass and the water conditions,etc. Simultaneity, the construction characteristic of TBM is also one of the factors which intensifying the occurrence of rock-burst. Utimately,it proposes the corresponding countermeasures by analysis for the occurrence regularity of rock-burst.