Analysis of Expanded Radius and Internal Expanding Pressure for Undrained Cylindrical Cavity Expansion

Abstract

Solutions for cylindrical cavity expansion have been studied widely in many aspects, but the analysis of expanded radius and internal expanding pressure is rarely found. In practical engineering, it is of great significance to determine the relationship of the initial expanded radius (a0) and expanding pressure (p). Based on the unified strength theory (UST), a theoretical relationship among the initial radius (a0), the expanded radius (a), and the expanding pressure (p) of the cylindrical cavity was derived under the condition of nondrainage. By using the theoretical relationship obtained, the limit expanding pressure (pu) and the stress and displacement fields were achieved, as well as the plastic-zone radius (rp). The influence of the intermediate principal stress coefficient (b) on stress fields and expanding pressure (pu) is also discussed. A parametric study showed that the stress and displacement fields in undrained conditions are only related to the initial radius (a0) and the expanding pressure (p), and the expanded radius (a) is a function of the expanding pressure (p) under a given initial radius (a0). In addition, the effect of intermediate principal stress on the pu is nonnegligible, whereas the effect on the stress is limited. At last, the validation of the proposed theoretical solution was demonstrated by comparing with the conventional theoretical solution and field test results.