(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. HydroChina Huadong Engineering Corporation，Hangzhou，Zhejiang 310014，China)
Abstract：Diversion tunnels of Jinping II hydropower station，which is located at high stress zone，Southwest China，encounter many geological disasters，such as rockburst，water bursting，collapse of tunnel and so on during construction. It is very important to master damage evolution of surrounding rock and to design effective supporting measures to prevent or relieve geological disaster. Therefore，acoustic emission(AE) test was carried out and law of damage evolution of marble was studied. Different damage of surrounding rock comes up in 10 m range before free face during TBM working；and main damage or cracking is developed in 7 m range；3 m location is the most severe after free face. Damage range of surrounding rock is about 9 m in direction of tunnel axis. Relaxation，damage and disturbed zone are distinguished by evolution law of AE events，energy release and mechanism of damage evolution. Relaxation and damage range of surrounding rock are 3，3–9，and 9–22 m far from tunnel wall，respectively. Mechanism of damage evolution is illuminated by AE and mechanical characteristics before and after peak strength of rock mass. The influences of sensor types and arrangement，environmental noise and geological conditions on testing result are discussed；and the directions to improve testing result are also pointed out.
