Application of Roof-Cutting and Pressure-Release Entry Retaining in Inclined Coal Seams: A Case Study

The technology of gob-side entry retaining as an important method to realize the sustainable development of coal resource has been widely applied in China's coal industry. However, when used in inclined thick coal seams, some disadvantages, such as complex strata pressure and gangue downslide, may cause serious entry accidents. To solve this issue, this study adopted a novel roof-cutting and pressure-release entry retaining (RPER) technology in inclined thick coal seams. First, the principle of RPER and the stability mechanism of gob-side entry surrounding rock were analyzed. Subsequently, the key technologies of the novel method including a new constant resistance anchor cable and a new type of directional cumulative blasting technique were proposed to improve the stress environment of retained entry, and an entry-side support system that guaranteed the effect of entry are described in detail. Finally, an industrial test of RPER in inclined thick coal seam was performed. Field monitoring data show that the entry retained by new method RPER was in a stable state, and the section of the retained entry after can meet the production needs of next panel. This work provides a safe and efficient nonpillar mining method in inclined thick coal seams, and it has significant significance for guiding other mines to carry out nonpillar mining in inclined thick seam.