Characteristics Analysis of Cavity Expansion with Anisotropic Initial Stress in a Two-Dimensional Numerical Model

Cavity expansion theory is used extensively in geotechnical engineering. The analytical solution of cavity expansion theory is all based on the isotropic initial stress in soil layer; however, due to the change of sedimentary environment and consolidated environment, the initial stress in soil layer is anisotropy. In this paper, the coefficient of lateral pressure at rest (K₀) is used to describe the degree of the anisotropy of the initial stress, and the FLAC software is employed to build a numerical model to analysis of the characters of cylindrical cavity expansion with anisotropic initial stress. The results indicate that the cavity shape is approximately ellipsoidal and the major axis of the ellipse locates at the direction of the major principal initial stress. In addition, the plastic zone around cavity is closely related to the initial stress state, and the largest range of plastic zone locates at the direction of the major principal initial stress. The influence of the undrained shear strength on the pressure-controlled cavity expansion process is also analyzed. With the increasing of undrained shear strength of soil, the largest range of plastic zone would decreases, which could decrease the effect of anisotropic initial stress on cavity expansion process.