Analytic solution for surrounding rock mass deformation of circular tunnels based on three-parameter unified strength theory

A closed-form solution is presented in this paper for the prediction of stress field, strain field, support force and radius of plastic division in the rock mass subjected to axisymmetric loads around circular openings, which has an important role when dealing with the deformation of tunnel rock mass. The rock mass is assumed to be governed by three parameter unified strength theory proposed by YU Maohong. Some important facts were considered, such as the in-situ 3D stress condition and the characteristic deformation of rock mass, the correct choice of strength theory which taking the intermediate principal stress into consideration. The results were found to be more practical and worthy of reference when the support design was performed.