Optimizing Coal Pillar Dimensions in Inclined Coal Seams: A Strain - Softening and Inclination - Dependent Analysis

The stability of coal pillar width in inclined coal seams is crucial for gob-side entry driving. This study explores how the inclination angle affects coal and rock mass properties, stress, displacement, and coal pillar dimensions. It analyzes stress field changes in the narrow coal pillar surrounding rock using theory, experiments, and simulations. Key results show that increasing inclination reduces coal and sandstone strength, with coal more sensitive; failure mechanisms change with angle, transitioning at 15°; a strain-softening model is developed, and coal pillar stress has a single-peak pattern; 6 ~ 7 m coal pillars have complex shear failures. The findings support inclined coal pillar strength and size optimization.