A novel analytical method and applications of tensile failure in roadways surrounding rock based on a stress deviator

Abstract This study investigates the widespread failure of surrounding rock caused by tensile and shear stresses in large-section mining roadways excavated within soft rock formations: a phenomenon that often leads to overall roadway instability. The mechanical expression for the third invariant J3 of the stress deviator in circular, non-uniformly loaded roadways was derived based on the analytical solution for stress distribution around circular openings. Both theoretical and numerical methods were employed to examine the distribution characteristics of J3, as well as the corresponding compressive-shear and tensile-shear plastic zones. These analyses provide new insights into the tensile failure mechanisms occurring in the shallow surrounding rock of large-section mining roadways. Using actual engineering as a case study, the study results indicate that under a stress field dominated by horizontal in situ stress, the lateral pressure coefficient (λ) intensifies the concentration of J3 and the extent of compressive-shear failure, but has a limited effect on the extent of negative J3 zones. In contrast, the roadway radius (R) significantly influences the concentration of J3, the development of compressive-shear failure, the extent of negative J3 zones, and the severity of tensile-shear failure. Therefore, large-section roadways are more susceptible to shallow tensile-shear failure. To mitigate such failure and suppress roadway deformation and convergence, measures such as optimizing the roadway cross-sectional shape, appropriately reducing the cross-sectional size, or increasing support density are recommended.