| The deformation and failure of surrounding rock caused by the mining of large dip coal seam are different from those of the common coal seam.Because of the asymmetry of the load on the overburden,the overburden breaking law also has special characteristics.Due to the lack of research on the deformation and fracture characteristics of overburden structure and the law of roof compression,the selection of support is unreasonable and the accidents of working face are frequent.Based on this,this article to the engineering background of TaoYuan mine ?1042 face,for large dip Angle of coal seam in the process of mining overburden rock fracture characteristics and law of mine pressure appear problems such as study,the main research conclusions are as follows:(1)A similar simulation experiment was designed to simulate the fracture characteristics and migration laws of dipping overlying strata in a large dip stope.Experimental results show that the large dip Angle of strata caving form to present the characteristics of asymmetric with working face advancing,the first caving rock will be compacted,and periodic weighting due within overburden stress arch structure,caving rock strata of the compaction degree is low,the formation of overburden rock deformation,damage and migration of asymmetric effect of restraint.(2)By establishing the mechanical model of overlying roof of large dip coal seam,the mechanical characteristics of surrounding rock of primary and periodic rupture of the basic roof under unbalanced load are studied,and the evolution law of deflection,bending moment and stress of the basic roof in the process of working face advancing is analyzed,and the mechanical criterion of the basic roof rupture of large dip coal seam is deduced.The theoretical analysis results show that the deflection of the roof of the primary fracture of the basic roof presents the asymmetry of the direction of the rock working face,and the maximum deflection is located at(A/2,1.836b/?),which shows the difference with the fracture characteristics of the horizontal roof.(3)By means of numerical simulation,the stress distribution of surrounding rock,the movement law of roof and the development characteristics of overlying rock fractures in coal seam with large dip Angle are studied.The results show that with the increase of dip Angle,the stress asymmetry of coal wall becomes more obvious,and the intensity of stress change at the upper and lower ends of working face gradually decreases.With the advance of working face,the difference between the peak value of stress concentration in the middle and the two ends increases,and the phenomenon of stress concentration in the middle region becomes more and more obvious.The height of overlying rock caving zone is positively correlated with the length of working face and negatively correlated with the dip Angle of coal seam.(4)Through the analysis of the field pressure data,it is found that the pressure law of working face presents the characteristics of time sequence,and the middle and middle upper parts are the first to be pressed.As the working face advances,the lower goaf is filled.The periodic pressure stepping distance between the lower part and the middle part of the working face is gradually larger than that of the middle part,the middle upper part and the upper part.The average difference between the 10 cycles of pressure stepping distance and that of the middle part,the middle upper part and the upper part is about 14%.The distribution characteristics of the working resistance along the tendency of the hydraulic support are analyzed by statistical analysis of the measured data,and the rationality of the results obtained from theoretical analysis and numerical simulation is verified.Figure[48]Table[7]Reference[81]... |
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