Theoretical solution for displacement and stress in strain-softening surrounding rock under hydraulic-mechanical coupling

Abstract

This study focuses on the stress and displacement of a circular opening that is excavated in a strain-softening rock mass under hydraulic-mechanical coupling. It follows the generalized Hoek-Brown (H-B) failure criterion. Moreover, an improved numerical method and stepwise procedure are proposed. This method considers the deterioration of the strength, deformation, and dilation angle. It also incorporates the hydraulic-mechanical coupling and the variation of elastic strain in the plastic region. Several examples are conducted to demonstrate the validity and accuracy of the proposed solution through MATLAB programming and FLAC software. Parametric studies are also conducted to highlight the influence of hydraulic–mechanical coupling on stress and displacement. Results show that in this case, stress confinement is lower and tunnel convergences are higher than the corresponding stresses and displacements obtained when those factors are not considered. The displacement and plastic radius are also larger than those obtained when hydraulic-mechanical coupling is not considered.