Research on stability and control of water-drenching broken roof roadway

To address roadway deformation and roof instability in a water-drenching return air rise affected by sandstone fissure water, and support failure due to water corrosion, field investigations, lab tests, theoretical analysis, and numerical simulations were used to study water-weakening rock behavior, factors influencing plastic zone radius and displacement, deformation and failure laws, and surrounding rock control technology. Results show: (1) The fundamental cause is water-weakening deterioration of surrounding rock mechanical properties, negatively correlated with moisture content; coal is much more susceptible than sandstone. (2) Based on elastoplastic and seepage theories, mining stress concentration factor, and a cyclic water immersion equivalent weakening model, formulas for plastic zone radius and displacement were derived, enabling mechanism diagnosis. These positively correlate with in-situ stress and initial seepage pressure, and negatively with support strength and surrounding rock cohesion. (3) Roadway displacement and stress correlate positively with moisture content and distribute symmetrically along the axis. Shallow surrounding rock fails in tension and shear, with intense plastic zones and fractures in the roof, shoulder corners, and sides. (4) Comparing three anchor cable reinforcement schemes, the combined support using 6.3 m anchor cables forms a 0.2 MPa continuous stress-connected zone. Effective stress depths reach 4.7 m (roof), 6.5 m (shoulder corners), and 2.6 m (sides), significantly improving the control effect with promising engineering application prospects.