Radius solution of plastic zone in soft rock tunnel surroundings considering joint damage

Based on the Hohai model, a creep constitutive model of viscoelastic-plastic soft rock with joint fracture damage is proposed to solve the rheological failure problem of soft rock tunnel surrounding rock. Based on the proposed creep model of rock with joint damage and the current analytical analysis method of circular tunnel, the analytical formulas of viscoelastic-viscoplastic stress and displacement of circular tunnel with joint damage surrounding rock are derived. ABAQUS finite element software is used to simulate the excavation of surrounding rock with different joint angles. The numerical solution is compared with the analytical solution to verify the accuracy of the theoretical formula. The results show that when the joint inclination is 45°, the displacement values of the two are 16.36mm and 16.87mm respectively, and the error of the two is 3.02%. The theoretical calculation is in good agreement with the numerical simulation results, thus verifying the rationality of the derived analytical formula of viscoelastic-viscoplastic stress and displacement of the soft rock tunnel with joint damage.