Study on the Coal–rock Ratio Effect of Asymmetric Deformation and Failure of the Gob–side Coal–rock Roadway in Gently Inclined Coal Seam

In order to reveal the deformation and failure characteristics and the stability of the rock surrounding the gob–side coal–rock roadway in gently inclined coal seam (GCRICS) under different coal–rock ratios, the deformation characteristics of the surrounding rocks under four different coal–rock ratios were studied by field investigation and numerical simulation. The results indicated that the degree of asymmetric deformation of GCRICS with different coal–rock ratios progressed from small to large: 1/5, 2/5, 3/5, and 4/5. With the gradual increase in the coal–rock ratio, the thickness of the coal seam increased, the mined-out area range increased in upper and lower sections, and the plastic zone in the roof strata of the roadway tended to gradually increase both vertically and along the incline downwards. This indicated the gradual increase in the influence of the upper and lower sections working face mining on the destruction of roof strata; the plastic zone range of the fine sandstone floor was less affected by the coal–rock ratio and underwent little change. Comprehensive analysis showed that the asymmetric deformation characteristics of the rock surrounding the roadway were greatly affected by the coal–rock ratio, and the larger the coal–rock ratio was, the more significant the asymmetric deformation characteristics were.