Research On Rules Of Surrouding Rock Movement For Backfill Mining And Entry Retaining With Superhigh-water Material

With the rapid development of national economy and increase in demand of coalresources year by year, the mining under buildings has become the important researchcontent in the field of coal mining in China. As a kind of no-pillar mining technology,backfill mining and entry retaining is a reasonable and effective way to exploit coalresources, increase coal recovery ratio and control the surface subsidence with thelarge scale of coal mining under buildings.Based on the basic properties of super-high-water material, this article studies themethods of backfill mining and entry retaining combined with the actual applicationsituation of this technology. Preliminary analysis of rules and control mechanism ofsurrouding rock movement of backfill mining and entry retaining withsuper-high-water material is made, though comprehensive use of the means oftheoretical analysis, numerical simulations and field observation for the application in1612working face of Rui-feng mining. The conclusions are as follows:(1) There are two main methods i.e. bag filling and hybrid filling withsuper-high-water material. Flexible use of different backfill mining methods can bemade according to the geological conditions of the mine, thereby expanding the rangeof application of backfill mining and entry retaining in mine.(2) The deformation and stress of surrounding rock of backfill mining and entryretaining with super-high-water material is mainly caused by three stages: drivage,working face mining and surrounding rock rheology, which show four conditions i.e.surface damage zone, plastic zone, yield zone and center elastic zone from the surfaceto the center.(3) The two main control methods of surrounding rock movement of backfillmining and entry retaining with super-high-water material are as follows:①thereinforce technology of anchor cable in entity coal side;②increasing the strength ofbag filling body by adopting the smaller volume ratio super-high-water material,maintaining stability of the bag filling body and improving filling rate of the goafwhich are mainly affected by mining factors, geological factors and mechanicalproperties of the filling body.(4) Adopting numerical simulation to simulate the rules of surrounding rockmovement of backfill mining and entry retaining with super-high-water material for goaf filling rate of70%,80%and90%, it shows the stress and deformation ofsurrounding rock decrease, and plastic zone reduces with the increase of goaf fillingrate.(5) The roof and floor convergence of roadway is within60mm, and thedeformation of roadway’s sides is within30mm in field measurement, which showthe roadway’s roof have been effectivly controlled by sides and retained entry canmeet the production requirements. the support pressure of bag filling body is less than2.5MPa, The roof strata have effectively undertaken the role of bearer and played thetransferring rock beam effect through the beam structure made of roof strata, coal andthe goaf filling body, reducing the load of filling bag filling; the roadway has beenused for three years with little deformation, so it can be used for a long time with lessmaintenance costs.