The Study On The Mechanism Of The Rock Outburst And The Geomechanics' Model Of The Subsidiary Tunnel In The Secondary Jinping Hydroelectric Power Station

Rock outburst is one of the main geologic hazards that restricted the tunnel construction. The domestic and overseas scholar studied the problem using varied method from the different views. At the present time, a unitized understanding has not been formed about the mechanism of the rock outburst. With the more and more understructure work the damage caused by the rock outburst increased. The problem is one of the important puzzles of the understructure geologic hazards. The study on mechanism of the rock outburst is the base of the burst intensity degree and the outburst forecasting prevention and cure of the outburst, so it's unguent and important to study the mechanism of the rock outburst. The working area-the secondary Jinping hydroelectric power station-has high ground stress and the subsidiary tunnel is a extra long embedding rocky tunnel. There are rock outburst in the exploration tunnel and the excavation part of the subsidiary tunnel. So this article's subject investigated is the subsidiary tunnel of the secondary Jinping Hydroelectric Power Station that has the theoretical and the practical dual significances.On the basis of the existent research findings, using the investigating the original mold-indoor testing-physical simulating-mechanism of the rock outburst-geomechanics study method we study thoroughly the reason of the rock outburst and get some research findings:(1) By studying the actual stress field of the engineering area, we find that the area is region of high stress and the original stress is the self-weight stress. Under the basis of the original stress field, by busing the numeric modeling the fracture plane of the subsidiary tunnel's secondary stress field, we find that the degree of secondary stress is high, the max vertical stress ranges from 95~103MPa and occurs on the arch springing.(2) Under the thorough studding the working area, we find the regularities of distribution of the rock outburst and degree the burst intensity. The most rock outburst's intensity is I or II.(3) Using the indoor rock mechanical test (including the uniaxial compression test of the rock deformation, triaxial compression test of the rock deformation and the rock outburst index test), we find that the rock damage's type is type II and the rock outburst index is moderated.