Deformation and stability investigations in 3-D of an excavated rock slope in a hydroelectric power station in China

A three-dimensional numerical model was built incorporating stratigraphy, geological structures and mechanical properties of rock masses and discontinuities to perform stress, deformation and stability analyses for an excavated slope in China using the 3DEC software. Based on this model, numerical modeling was conducted to study the effect of boundary conditions, lateral stress ratio, and rock mass and fault parameter variability and uncertainty on the deformation and stability of the excavated rock slope. Displacement comparisons were made between the field monitoring values and numerical simulations. In the 3DEC modeling, both the stress and zero displacement boundary conditions were used to represent the lateral boundaries of the slope. Because the lateral boundaries were placed not far enough from the faults, the stress boundary conditions provided realistic results compared to the zero displacement boundary conditions. The best comparison with the field monitoring values were obtained when k(0max) is in the range 1-1.5 and k(0min) = 0.7. The best comparison between the numerical results and the monitoring data were obtained when the rock mass and fault property values were reduced by about 30% from the average material property values. The modeling approaches given in this paper should be useful in performing realistic three-dimensional stress, deformation and stability analysis of rock slopes.