Combined Support Technology of Retained Entry in Large Mining Height Face with Double Roadways Layout

Abstract

The stability of retained roadway plays an important role in the safety production of coal mine underground working face. Taking the 21,101 auxiliary haulage gate in Yaping Mine as the engineering background, the supporting technology was systematically studied. Firstly, based on the previous situation of pillar setting and surrounding rock failure and deformation in double roadway layout, the reasonable size of pillar between roadways was studied. The width of the broken zone was realized as 2.95 m by theoretical analysis, and then the width of pillar between roadways was determined as 7.95 m. On this basis, the law of stress evolution and retained roadway deformation with the pillar width of 6 m, 8 m, 10 m, 12 m, 15 m under the influence of two times mining were analyzed, comprehensive analyzed the above research results, 8 m in width of pillar between roadways was determined. Secondly, the failure rules of pillar between roadways, the failure rules and the failure process of retained roadways during two times mining were revealed: the range between 70 m in front of the work and 80 m behind the work was determined as the mining influence area according to the damage degree of coal pillar, the failure depth of surrounding rock in retained roadway during the two times mining was the largest in the pillar side, the second in the roof and the coal wall side, the smallest in the floor, and the damage degree was the largest in pillar side, the second in floor, the smaller in roof and wall, and the overall failure of roadway was asymmetric. Finally, on the basis of the above research results, considering all kinds of influencing factors and technical difficulties of retained roadway surrounding rock support, the system analysis method was used to determine the combined support technology with high strength allowable cables support + asymmetric cables support + bolts support system + concrete floor-allowable pressure non-repeated supports dynamic strengthening support. Practice shows that the combined support technology is scientific and reliable, which can meet the safety mining requirements in large mining height face with double roadways layout.