An innovative equivalent width supporting technology for sustaining large-cross section roadway in thick coal seam

Abstract

As energy structures have been adjusted in China, the coal industry has begun to develop large and highly productive coal bases. Along with the problems associated with high intensity mining, support for large cross-section roadways has become a major issue. To enhance the stability of surrounding rock masses of roadways with large cross-sections and to reduce support costs, an innovative supporting technological tool referred to as equivalent width supporting (EWS) technology is studied and applied. The premise of EWS technology is to transform large cross-sections into common roadway cross-sections by using support materials of high-yielding load capacities. The basis of this technology concerns how to measure pressure levels of the equivalent part and how to find high-yielding load capacity supporting materials. In this study, computational formulas for supporting stress of the equivalent part are presented. In turn, a new supporting material called high-yielding load prop is developed. Structural and load-deformation characteristics of this prop are studied, and results show that this prop could provide stable loads ranging from 400 to 800 kN over a small shrinkage distance of less than 10 mm. The load capacity of the prop can be adjusted with a small change made to its geometry. It is shown that EWS technology perform well in field applications of the Ta Shan coal mine in China. The onsite experiment results show that EWS technology employing high-yielding load props can enhance the stability of surrounding rock and can resist dynamic pressures generated by excavation. In addition, relative to original supporting costs, EWS technology can reduce overall supporting costs by 63.8%.