Study on the Reasonable Width of Coal Pillars in Gob-Side Entry Excavation for the 3308 Working Face of Dongtan Coal Mine

With the increasing depth of coal resource mining, the stability of coal pillars during gob-side entry excavation has become a critical technical challenge restricting mine safety. This study focuses on the 3308 working face of Dongtan Coal Mine, analyzing the effects of different coal pillar widths on stress distribution, vertical displacement, and horizontal displacement in surrounding rock using FLAC^3D numerical simulation. Field trials were conducted to verify the optimized design. The results show that when the coal pillar width is 4m, severe stress concentration occurs on both sides of the pillar, leading to significant deformation in surrounding rock, increased roof subsidence, and poor coal pillar stability. Increasing the pillar width to 5 m effectively alleviates stress concentration and reduces deformation but compromises resource recovery efficiency. A coal pillar width of 4.5 m was determined to provide an optimal balance between stability and resource utilization. Based on this width, an enhanced support design incorporating grouted anchor bolts, frictional yielding, and shear-resistant reinforcement was implemented, significantly improving surrounding rock stability. Industrial trials demonstrated that the optimized support effectively reduced the maximum roof subsidence to 243 mm and controlled surrounding rock deformation, ensuring safe production. This study provides theoretical guidance and practical solutions for optimizing coal pillar widths and surrounding rock control in gob-side entry mining under similar geological conditions.