Flexible roadway protection technology in medium-thickness coal seam with large dip angle

Abstract

ABSTRACTAccording to the caving and accumulation characteristics of gangue in goaf of a large dip coal seam, a new flexible roadway protection (FRP) technology was put forward. Meanwhile, four types were designed of blocking gangue steel mesh: “1 type”, “wave type”, “L type “ and “L-wave type”, to adapt to the characteristics of overlying strata and the impact strength of gangue in the different large dip angles working face. Blocking gangue steel mesh could convert the impact (harmful behavior) of the rolling gangue into the filling force (advantageous behavior) of the roadside support body. Consequently, a roadside support body made of compacted gangue as aggregate was formed. Besides, the calculation formulas for the impact velocity and the maximum impact force at the moment of contact between the gangue and the steel mesh was attained through the mechanical analysis. On this basis, the strength checking method for steel mesh was obtained. The application of FRP technology to engineering practice indicates that this technology has the features of high bearing capacity, strong impact resistance, simple process, low cost, etc. It is suitable for the application of the gob-side entry retaining for medium-thick coal seam with large dip angle. The introduction of FRP technology has significantly expanded the application scope of the gob-side entry retaining technology.