1.School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo ,China;2.Collaborative Innovation Center for Coal Safety Production,Jiaozuo ,China;3.Sichuan Huayingshan-Longtan Coal Power Co.,Ltd.,Guang′an ,China; 4.Liyuanhe Coal Mine,Xuangang Coal and Electricity Co.,Ltd.，Datong Coal Mine Group,Yuanping ,China

In view of the risk of instability of surrounding rock and water inrush along the roadway excavated in water-bearing gob in gently inclined coal seams,and in order to analyze and evaluate the damage laws and anti-water rupture capabilities of the waterproof coal pillars and surrounding coal seams,the optimal support control technology for roadway along gob was obtained.Based on the theoretical research and field practice of coal pillar retention along roadway excavation,the theoretical calculation of the width of coal pillar retention in roadway excavation along water-bearing gob was studied and the fluid-solid coupling-mechanical reaction of the coal pillars in roadway protection was analyzed comprehensively by using orthogonal test design and FLAC3D numerical simulation method.The sensitivity of factors affecting the stability of roadway pillars and the width of coal pillars in different roadways were analyzed.The distribution characteristics of stress field,displacement field,pore water pressure of surrounding rock and their effects were optimized under different supporting parameters.The research results show that: under the situation of coal pillars with a width of 12 to 18 m,a head pressure of 0 to 0.3 MPa,and a coal seam inclination of 2° to 10°,the primary and secondary order of the factors affecting the stability of coal pillars in roadway protection is: water pressure>coal seam dip angle>coal pillar width; under the action of the maximum head pressure,the reasonable width of the coal pillar for protecting the roadway is 12 m; the optimal support parameters of No.2214 return air roadway are determined.Underground industrial tests have verified the safety and economy of retaining coal pillars with a width of 12 m.The displacement of surrounding rock surface along empty roadways with active and passive combined support parameters is within the allowable range of the project.