Abstract:

Traditional cylindrical cavity expansion theory is based on the isotropic initial stress supposition. However, the cylindrical cavity is usually expanded in case of horizontal initial stress unequal to vertical initial stress, such as the horizontal directional drilling in tunnel engineering. A new elastoplastic cylindrical cavity expansion solution is introduced, in which the anisotropic initial stress is explicitly considered. Case study results indicate that the cylindrical cavity expansion with anisotropic initial stress yields a larger plastic zone than that with isotropic initial stress when the rest geometrical and geomaterial parameters are the same. The results also demonstrate that the cylindrical cavity expansion with anisotropic initial stress results in a smaller ultimate expansive pressure than that with isotropic initial stress.

Key words: cylindrical cavity expansion, anisotropic initial stress, plastic zone, ultimate expansive pressure