Abstract:

In order to improve the stability of weakly cemented soft rock roadways, the failure mechanism and stability control technology were systematically investigated. Specifically, physical and mechanical tests, mineral composition analysis, numerical simulations, and field tests were comprehensively employed, with the I0227²03 working face in the West No.3 mining district of the Third Coal Mine serving as the engineering background. The results show that the weakly cemented soft rock roadway was characterized by three major features: non-uniform spatial large deformation, strong timeliness, and significant water-immersion deterioration. The low strength of the coal-rock mass and the high content of clay minerals were identified as the intrinsic causes of the swelling, softening, and deformation of the surrounding rock. Under the superimposed action of in-situ stress and top-coal caving impact load, insufficient original support strength was found to be the external driving factor for the large roadway deformation. Consequently, a vicious deformation cycle was formed, comprising "roof subsidence squeezing the coal side-coal side bulging squeezing the floor". Based on the "roof-side-floor" synergistic bearing concept, conventional anchor cables were adopted for roadway side reinforcement, grouting anchor cables were employed for floor reinforcement, and anchoring force was simultaneously enhanced. Numerical simulations demonstrated that, compared with the original scheme, the optimized scheme reduced the convergence between roof and floor by 75.7% and the convergence of the two sides by 75.4%. During the field test, the maximum roof convergence was 74 mm, the maximum floor heave was 43 mm, and the maximum convergence of the two sides was 88 mm. The surrounding rock deformation is within a controllable range, and the optimized scheme is thereby validated to be effective.

Key words: weakly cemented soft rock, roadway failure, stability control, surrounding rock deformation, synergistic bearing