Study On Evolution Characteristics Of Mining-induced Stress And Fracture Of Coal Seam With Erosion Zone Of Fully Mechanized Caving Mining

The third panel area of Baode Coal Mine is eroded by a wide range of erosion zone,which is a common geological abnormal body in the process of working face stoping and seriously affects the safe stoping of working face.On the one hand,the erosion of the erosion zone on the coal seam reduces the amount of recoverable resources.And the rock of the erosion zone is sandstone or conglomerate with high hardness.It is easy to damage coal mining equipment when cutting erosion zone.On the other hand,the change of roof lithology is unfavorable to roadway support,which is easy to lead to roof accidents.In order to master the characteristics of mine pressure in the process of erosion coal seam mining,the 81308 working face Shendong Baode Coal Mine was taken as the research background,based on the geological occurrence conditions and mining parameters of the mine and working face.By means of theoretical analysis,similarity simulation and numerical simulation,the evolution characteristics of mining-induced stress and fracture of coal seam with erosion zone in fully mechanized caving mining were studied.First of all,the erosion characteristics of the erosion zone in third panel area of Baode Coal Mine,the mining parameters of 81308 working face and the mechanical parameters of coal and rock mass were obtained through field investigation,which provided data support for theoretical analysis,similarity simulation and numerical simulation tests.Secondly,the stope pressure model under the influence of erosion zone was established,and the development of fracture zone,roof fracture and support load characteristics of the working face under erosion zone were analyzed theoretically.It is found that after the erosion zone erodes the coal seam,the mining height decreases,the direct roof thickness increases,the development height of two belts in the stope decreases.The beam structure was formed after the roof of the erosion section was broken,and the short cantilever beam structure was formed behind the coal wall after the roof of the non-erosion section was broken.In order to ensure the stability of overlying rock structure,the erosion section needs to provide support of 9437~10558kN,while the non-erosion section needs to provide support of 10859~12108kN.Thirdly,the similar simulation model and the FLAC and UDEC numerical simulation models were established to explore the influence of erosion on overburden rock breaking,fracture development and stress distribution characteristics.The study found that :(1)The coal seam in the erosion section is affected by the erosion of erosion zone to reduce the mining height.Meanwhile,the direct roof thickness is large and the goaf filling degree is high.The beam structure is formed after the basic roof rock breaks in the erosion section,and the roof structure is relatively stable.During the mining in the non-erosion section,with large mining height and large separation space after direct roof collapse,the roof slides down and becomes unstable as a whole,the short cantilever beam structure is formed behind the coal wall,and the working face shows strong mine pressure.(2)The stress of stope is symmetrically arched when the erosion zone is mined.When the stope reaches the non-erosion section,the stope stress presents asymmetric arch distribution,and the arch height in the erosion section is lower than that in the non-erosion section.The distance between the position of vertical stress peak and coal wall in the erosion section is smaller than that in the nonerosion section.(3)The development height of the erosion area fracture zone is lower than that of the non-erosion zone because of the influence of erosion zone on the working face.Finally,based on the above research results,combined with the erosion characteristics of the erosion zone of 81308 working face,the influence of the erosion zone on the mining of working face was analyzed,and the measures of passing erosion zone were proposed.The results of this study can be used for reference to the mining of erosion coal seam and the control of surrounding rock.Figure [43] table [7] reference [67]...