Numerical Simulation Analysis For Wall Rock Stability Of Underground Cavern

The technology of underground space is the developmental trend of Geotechnical engineering field in this century. Many giant water conservancy and hydroelectric power project lied in the remote mountains and gorge. Overground space is very limited, making use of underground space solved the space problem of hinge disposal, at the same time, it could take full advantage of water level difference to advance the using efficiency of water power. As to the large and complex underground caves, the stability problem of wall rock during the process of underground cave's excavating is connected with the constructible cost and management benefit of the whole power station project. The problem is worth of lucubrating.In this paper, taking example of 1# tunnel of Nuozhadu hydroelectric power station, it analyzed and evaluated the intimately correlative problems of wall rock stability with nonlinear finite-element method. First, combined with the terrain and physiognomy characters in the project field, built the 3D model of the dam section, according to the geodesic data of terra stress, in virtue of ANSYS finite-element program to back-calculate and to analyze, confirmed the initial geostress field and the boundary stress condition at the damsite zone; Then, simulated the whole process of the underground cave's excavating with elastic-plastic finite-element program analysis method, calculated and analyzed the change of the second stress field and deformation field and distributing character of the plastic zone in the course of the underground cave's excavating and after excavating, evaluated and compared the stability of cavity in the different wall rock;At last, analyzed rock creep to have an effect on lining after supporting with viocoelastic finite-element analysis method, carried through some beneficial exploration on the rock's rheology, synthetically evaluated the stability of the underground cavity.