Study on the width of section coal pillar based on plastic zone theory

To ensure the stability of the mining roadway of 30208 fully mechanized mining face in 3⁻¹ coal seam of Nanliang Coal Mine and maximize the recovery of coal resources, through theoretical analysis and field measurement, the reasonable width of section coal pillar is calculated. The calculation method of the width of the plastic zone on the side of the coal pillar goaf and the side of the roadway is derived, and the distance between the fracture position of the lateral main roof of the upper section goaf and the edge of the goaf is determined. Based on the limit equilibrium theory and D-P criterion, the calculation model of the lateral plastic zone of the rectangular roadway is established, and the width of the plastic zone on the coal pillar side and the roadway side of the working face is calculated. Based on the principle of preventing plastic zone from penetrating and retaining sufficient elastic core area, the calculation formula of minimum safety width of coal pillar is determined. The field monitoring results show that the deformation of roadway surrounding rock experiences three stages of undisturbed, deformation acceleration and deformation deceleration with the advance of working face. The maximum convergence of roof and floor and two sides is 149.9 mm and 55.4 mm, respectively, and the stability of coal pillar is good, which verifies the rationality of the calculation method.