Steady analysis of gob-side entry retaining formed by roof fracturing and control techniques by optimizing mine pressure

Based on the mechanism of the gob-side entry retaining formed by roof fracturing,the evolutionary laws of roof structures were theoretically studied during the entire entry retaining process. Accordingly,the retained entry was divided into the advanced pressure region in front of the mining panel,the dynamic and stable pressure regions behind the mining panel. According to the dynamic behaviors of the roof strata,an innovative entry control approach by artifi-cially building a stable surrounding rock structure has been proposed in the study. In this approach, the bulking gangues were designed as bearing bodies at the gob area. The constant resistance and large deformation anchor cables, gangue prevention structures and pier-beam unit supports were designed as entry-in support bodies. Finally,the ap-proach was tested at a thick coal seam longwall mining panel. Field monitoring showed that the stress concentration ar-ea was transferred to the gob area and the load-bearing capacity of the gangues was fully utilized after adopting the ap-proach. The support pressure first increased and then maintained constant to build the stable surrounding rock structure. The indexes of the retained entry could meet the requirements of next panel. This study provides an effective ap-proach for entry control in non-pillar longwall mining.