Expansion of Cavities Embedded in Cohesionless Elastoplastic Half-Space and Subjected to Anisotropic Stress Field

Abstract

Cavity expansion theories are employed in a wide range of geotechnical applications including interpretation of pressure meter tests, evaluation of shaft capacity of piles, and pulling forces for horizontal directional drilling. Most of these theories assume infinite medium and isotropic stress field, which may not be justified for many applications. The main objectives of this paper are two folds: to investigate the effects of the free surface, stress gradient, and in situ stress anisotropy on the displacements during the expansion phase of cavities embedded in dilatant sands; and to establish correction factors to account for these effects. The investigation was conducted using two-dimensional finite element analyses. It was found that the cavity expansion theory due to Yu and Houlsby (Geotechnique 41:173–183, 1991) can be used reliably for cases subjected to an initial isotropic stress and embedment depth to diameter ratio of 20 or higher. However, it becomes inaccurate for shallow embedment depth and/or stress anisotropy conditions. An analytical procedure to account for the effects of embedment and/or stress anisotropy was proposed. The applicability of the proposed procedure was demonstrated for a wide range of soil properties and geometrical configurations. The results obtained confirmed its ability to estimate the cavity pressures within 10 % of the values obtained using FEA calculations.