Abstract:

The traditional cavity expansion theory, which is based on the isotropic initial stress in soil layer, could not be used to the situation with anisotropic initial stress in soil layer. A two-dimensional undrained numerical model is conducted to simulate the pressure-controlled cavity expansion process with anisotropic initial stress. Through analyzing the cavity shape, the distribution of plastic zone and excess pore water pressure, the characters of the pressure-controlled cavity expansion with anisotropic initial stress is obtained. The results indicate that the radial displacement, plastic zone and excess pore water pressure around the cavity is not equal in all directions in case of pressure-controlled cavity expansion with anisotropic initial stress, which is different with the traditional cavity expansion. The results also show that the plastic zone of cavity expansion with anisotropic initial stress is larger than that of cavity expansion with isotropic initial stress. It is concluded that it would be unsafe if the traditional cavity expansion theory based on the isotropic initial stress supposition is used to analyze projects with anisotropic initial stress.

Key words: cavity expansion, pressure control, anisotropic initial stress, numerical simulation