Principal stress rotation effect and multi-factor coupling support optimization in roadways of inclined coal seams

Aiming at the effect of principal stress rotation (PSR) in gently inclined coal seam roadways, this study has established a strength criterion that comprehensively considers the coupling effects of multiple factors. Through integrated theoretical analysis, numerical simulation, and physical model testing, this study quantifies the influence of critical parameters on support stability, encompassing principal stress deflection angle, bolt support angle, damage factor, principal stress ratio, and friction coefficient. Quantitative analysis demonstrates that parameter sensitivity exhibits the following hierarchy: damage factor > principal stress deflection angle > principal stress ratio > friction coefficient. The investigation determines optimal roof support angles of 45-55°, with diminished angle sensitivity observed under high dip conditions (ψ ≥ 60°). Digital Image Correlation (DIC) and Electro Mechanical Systems (MEMS) fiber optic sensors were utilized to monitor principal stress rotation, providing high-precision measurements of stress field evolution. This analysis reveals asymmetric PSR distribution characteristics in the roof structure, manifesting rotation angles of 84.23° and 58.45° on the left and right sides respectively. These findings facilitate the development of a regionalized differential support methodology. Field implementation validates the theoretical framework, demonstrating substantial improvements in roadway stability.