Reasonable width analysis of coal pillar preserving gateway in fully-mechanized sub-level caving

Based on the great deformation and difficult supporting characteristics of surrounding rocks in preserving coal pillar of gateway in fully-mechanized sub-level caving, the reasonable coal pillar width preserving formula is obtained by applying the theory of elastic-plastic limited equilibrium. According to the gateway of No. 1151(3) fully-mechanized sub-level caving mining face in Xieqiao Mine, the mechanical relations between coal-pillar width and factors which affect how to preserve reasonable coal-pillar are qualitatively and quantitatively analyzed. The results show that increasing support-force, optimizing support-parameters and increasing side-force of gob are effective methods to improve the holistic resistibility of surrounding rocks and coal pillar and assure the stability of gateway. The research result will provide some scientific references for preserving reasonable coal pillar for the similar mine coals.