Analysis on textural stress and rock failure of diversion tunnels

The textural stress has great effect on the stability of rock.According to the measured geo-stress data,through FEM and combined with the linear multivariate regression method,the geo-stress field was conducted.Based on Yu Maohong’s generalized twin-shear strength theory,the failure type was classified into the generalized tension,the generalized compression the and generalized shear.Using these methods,a diversion tunnel of a large-scale hydropower station was analyzed to study the stress distribution,the peculiarity and process of failure.It was shown that the stress concentration was located at the bottom of the wall and the arch top,the stress in the wall was little and the failure happened at the bottom of the wall and the arch top,then the bottom board and some areas far from the tunnel.Under the condition without considering textural stress,the stress concentration area located in the wall and the failure happened at the bottom of the wall,then in the middle of the wall and at the arch top,the failure elements were concentrat around the tunnel.Based on the deformation observation,the results considering textural stress could reflect the real failure process of tunnels.