Deformation mechanism and control technology of gob-side entry retaining in shallow buried coal seam

For the rib spalling issue caused by gob-side entry retaining in shallow coal seam mining in China's northwestern region, we take the 115101 working face of Tianlong Da Haize Coal Mine as an example. By employing a combination of similarity material simulation and numerical simulation, the deformation mechanism of the roadway is systematically investigated. Through theoretical calculations and field applications, relevant roadway deformation control technologies are summarized and proposed. The results show that: the suspended roof structure in the gob area leads to a significant increase in vertical stress, while the insufficient strength of temporary support causes the gob roof to subside before the flexible formwork concrete wall reaches its designed strength. As a result, the flexible formwork wall cannot fully exert its active support function, leading to excessive pressure on the coal rib and subsequent rib spalling. Based on these findings, a "stress regulation-strength enhancement" collaborative control technology was proposed: on one hand, pressure-relief borehole groups are implemented in the coal rib to effectively reduce stress concentration factors; on the other hand, high pre-tensioned bolts (and cables) are employed to reinforce temporary support, with the concurrent extension of the temporary lagging support zone to 100 meters to secure both sufficient initial setting time and necessary space for the flexible formwork wall's proper curing.Field trials demonstrated that this technology reduced roadway rib convergence by 60% and controlled rib spalling within 40 mm. This study provides a quantifiable optimization method for support parameters in shallow buried coal seams and offers valuable technical guidance for mines under similar geological conditions.