Research On Upward Mining In Room-Column Goafs Of Shallow Coal Seam With Close Distance In Hanjiawan Coal Mine

The ascending mining in the residual area is essentially the recovery of the remaining coal seam above the goaf.The core problem of ascending mining is the joint structure of the upper coal bed under the joint influence of upper and lower coal seam mining.Therefore,the study of interbedded rock formations in the upward mining of residual areas is useful for promoting the development of up mining technology and efficiently recovering historical abandoned coal seams.This paper relies on the National Natural Science Foundation of China for“Research on the structure and instability mechanism of the surrounding rock in the upper and lower remnants of the shallow-buried room-column goafs”.The uplift of 1-2 coal in the house-pillar gob of the Hanjiawan Mine is Background,through experimental research.theoretical analysis,and numerical simulation methods,the interbedded rock stratum structure and feasibility determination theory and method for upward mining of room and pillar goafs have been studied.The main research contents and results are as follows:(1)Analysis of similar simulation experiments shows that 2-2 coal,1-2 coal mining,coal pillars and interbedded rock formations are basically not deformed and damaged,and 2-2 coal roofs form typical beam and slab structures.Based on the theoretical analysis,the mechanical model of the interbedded rock formations in the goaf-type goaf is built-the beamless cover structure.The mechanical analysis of the interbedded rock strata and the derivation of interbedded rock strata in the goaf-type goaf are obtained.Stability criteria.(2)Using the FLAC3D numerical software to simulate the ascending mining of 1-2 coal in Hanjiawan chamber pillar gob,the simulation results show that the“pressure relief arch”and“pressurized arch”appear alternately in the roof rock formation in the goaf area.In this case,the“boost arch”of the middle pillar is the largest,and it does not reach the bottom of the upper coal seam.The interlayer rock layer exists as a control layer for the upward mining of the pillar-type goaf.According to the judgment theory of the ascending gouging technology in the gob-type goaf and the conditions in Hanjiawan,the tensile strength and shear strength of the control layer between 1-2 coal ascending in mining are all below the ultimate strength,so the control layer can remain stable.Hanjiawan 1-2 coal mining is safe and feasible.