Nonlinear visco-elasto-plastic solution of surrounding rock considering seepage force and 3-D Hoek–Brown failure criterion

This paper focuses on the influence of intermediate principal stress and seepage force on visco-elasto-plastic solution of surrounding rock. By assuming that the surrounding rock satisfies the 3-D Hoek–Brown failure criterion and Hohai model, the stress, displacement and long-term deformation of tunnel are obtained. For elasto-plastic surrounding rock, an analytical approach was presented. For strain-softening surrounding rock, the potential plastic zone was subdivided into a finite number of concentric annuli and a numerical model was presented. Thus, based on 3-D Hoek–Brown failure criterion and Hohai model, the nonlinear visco-elasto-plastic models considering the intermediate principal stress and seepage force were proposed for elasto-plastic and strain-softening surrounding rock. The accuracy of the proposed approaches was validated with the published results in which the intermediate principal stress was not considered. Comparisons illustrate that the influence of seepage force on 3-D Hoek–Brown fai...