| In order to solve the problems of regenerated roof fracture and support sliding instability in the lower slicing induced mining face of steeply dipping coal seams,we consider the geological and engineering conditions of workface 1212(3)steeply dipping coal seam mining face which is thick and soft in Panbei coal mine of Huainan,Based on theoretical calculation,similar simulation test based on distributed optical fiber and acoustic emission monitoring technology,numerical simulation test based on coal measure stratum structure modeling technology,secondary diagenesis test of gangue confined compression and consolidation,field test of borehole detection based on three-dimensional imaging technology and other research methods,the overlying strata fracture migration and stress evolution and roof regeneration of upper slicing mining were studied The mechanical characteristics,the broken and multi physical field response of the regenerated roof,and the stability control mechanism of the support and the regenerated roof were systematically studied.(1)The characteristics of fracture migration and stress evolution of overlying strata in upper slicing mining of steeply dipping coal seam.The mechanical model of overlying strata breaking was established,and the distribution law of deflection and maximum tensile and shear stress of sandy mudstone layer was analyzed.The mechanical driving mechanism of overlying strata caving structure was obtained.The physical and numerical models of upper slicing mining were established.The characteristics of overburden fracture and displacement stress evolution of upper slicing mining were analyzed.Two kinds of filling shape characteristics of gangue in goaf were determined.(2)Study on the mechanical characteristics of the regenerated roof in the mining of steeply dipping coal seam.The mineral types and contents of mudstone and sandy mudstone which constitute the regenerated roof were measured,and the cementation regeneration capacity of broken rock block was obtained.The side limit compression test was carried out on the broken rock block.The influence degree and action mechanism of water content,compression rate,particle size and volume grade on the compressive axial stress and secondary consolidation diagenetic specimen were analyzed.The quantitative characterization of mechanical properties of cementation was given under four factors.The fracture distribution and the consolidation characteristics of the surrounding rock with low degree of cementation were found in the field drilling of the regenerated roof.(3)The characteristics of broken roof and multi physical field response in steeply dipping coal seam were analyzed.Based on the similar simulation and numerical simulation experiments,the zonal evolution of the fracture tendency of the lower layered regenerated roof,the response law of the optical fiber strain and acoustic emission energy of the regenerated rock mass deformation,and the evolution characteristics of the stress shell of the regenerated roof were studied.The mechanism of the fracture of the lower middle cantilever beam and the fracture of the high hinged rock beam of the lower layered support was clarified,and it was revealed that the upper part of the lower layered support was the key prevention and control areas of support and regenerated roof.(4)Research on stability control mechanism of support and regenerated roof in steeply dipping coal seam.The relationship between support and surrounding rock was determined,the mechanical model of support back sliding and rib spalling was established,the relationship between support back sliding and coal seam dip angle,friction coefficient between roof and floor and support top beam and side protection force of side protection plate was studied,and the relationship between rib spalling and coal seam dip angle,regenerated roof load,coal cohesion and internal friction angle was analyzed.This paper puts forward the three-in-one zoning cooperative control measures of regenerated roof mesh grouting,"three-stand" combined anti-sliding with support jack,coal wall mesh grouting plus construction of glass fiber reinforced plastic anchor rod of "side protection,roof protection,frame protection." We monitor the working resistance and skew angle of support,coal wall rib position and step distance,and evaluate the effect of "three-in-one" zoning cooperative control of support-surrounding rock system and coal wall stability.Figure:[98];table:[22];reference:[185];... |
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