Asymmetric deformation characteristics and stress deviator distribution in roadways under principal stress reorientation

Asymmetric deformation and failure of surrounding rock are frequently observed in mountain tunnels and deep mining roadways, yet the underlying mechanisms remain poorly understood. To investigate asymmetric failure in roadways adjacent to fault structures and mining panels, this study adopts an integrated approach combining theoretical derivation, numerical simulation, and field application, with particular emphasis on the second invariant of the stress deviator (J₂) in the surrounding rock. Based on the stress solution for a circular opening, an analytical expression for J₂ (distortion energy) is derived by considering the reorientation of principal stresses. The study demonstrates that both the increase and reorientation of principal stresses induced by fault–mining interaction jointly govern the spatial distribution of J₂ and the resulting asymmetric failure behavior. Specifically, the principal stress rotation angle determines the location of J₂ concentration, whereas the principal stress ratio controls its magnitude. To mitigate asymmetric failure, it is recommended to optimize the J₂ state through adjustments in roadway size, geometry, and support systems, while simultaneously controlling the asymmetric concentration of stress deviator to enhance roadway stability. This study systematically elucidates the chain mechanism of asymmetric surrounding rock failure driven by principal stress, and further proposes a rational asymmetric joint control strategy, providing theoretical guidance for similar underground engineering conditions.