Thick sandstone roof strata exacerbate surrounding rock deformation and failure in roadways, posing a severe threat to safe and efficient coal mine production. To address the challenge of controlling surrounding rock in high-stress roadways under such conditions, a novel composite roof cutting and pressure-relief method leveraging the dilation characteristics of gangue was hereby proposed. Firstly, numerical simulations were employed to establish a gangue model, and investigations were conducted into the in-fluence of gangue size and placement patterns on its dilation behavior and bearing capacity. The results revealed that within a specific size range (excluding extreme particle sizes such as the maximum and minimum), smaller gangue particles with more irregular placement exhibited a higher dilation coefficient and superior bearing performance. Building upon this principle, the composite roof cutting and pressure-relief method was further formulated, accompanied by the development of a theoretical roof structure model elucidating its control mechanism. Secondly, numerical simulations were performed to assess the control effectiveness of the new method, and comparative analyses were carried out to verify its efficacy. The results demonstrated that this method effectively utilized gangue dilation characteristics, significantly minimizing overlying strata subsidence and alleviating surrounding rock stress on the solid coal side of the roadway. Finally, field engineering trials were conducted. Monitoring data confirmed that the new method successfully reduced surrounding rock stress, optimized the roadway stress environment, effectively suppressed surrounding rock deformation, and achieved the objective of roadway protection. Overall, the re-search findings provide significant references for controlling surrounding rock deformation in high-stress roadways under thick sandstone roof conditions.

Roadways driven along the floor of thick coal seams, while retaining the top coal, form “thick coal seam floor roadways.” These large-section roadways feature a composite coal-rock roof and weak coal ribs, leading to low overall strength and poor stability of the surrounding rock. Significant deformation and “necking” often occur, accompanied by roof falls and rib spalling, which are exacerbated under high stress or adverse geology, threatening mine safety and production. In this study, the 2201 haulage gateway in Yingpanhao Coal Mine is investigated to address surrounding rock control in such deep roadways. Using field investigation, theoretical analysis, numerical simulation, and similar simulation tests, the failure mechanisms of ribs and roofs are analyzed. Rib failure is characterized by tensile fracture in the shallow zone, splitting failure in the medium-depth zone, and incomplete conjugate shear in the deep zone. Corresponding mechanical models are established, and a method for calculating total rib failure depth—combining tensile/splitting and shear failure depths—is proposed, along with a bolt length design formula. Based on this, a synergistic roof-and-rib support technology is developed. The failure mechanism and optimal support scheme are validated through simulation tests and successfully applied in the field, demonstrating satisfactory performance. The findings provide a valuable reference for support design in similar mining roadways.

The high stress environment and hard roof conditions seriously limit the application of gob-side roadway retaining. To achieve non-coal pillar mining, this study proposes a novel method combining roadside filling and roof cutting under stress-release and strong support synergy. Mechanical modeling reveals surrounding rock failure mechanisms in high-stress gob-side roadway retaining. Numerical simulations show the new method reduces surrounding rock stress/displacement more effectively than conventional gob-side roadway retaining. Optimized parameters were validated via field tests, confirming significant control of rock deformation under complex high-stress conditions. The method successfully enables non-coal pillar mining, providing a scientific basis for similar applications.