Study On System Complexity Between Coal Cutting And Coal Loading At Arc Segment In Longwall Fully Mechanized Caving Face In Steeply Dipping Seam

In order to control the stability of support system in working face,some mines with steeply dipping seam arrange the haulage way horizontally along the roof,and then joint the horizontal section and inclined liner section by "arc",that is,the arc segment layout.After the arrangement transforms the problem of supporting the lower end in complex steeply dipping seam into that in horizontal working face,the complexity of coal cutting and coal loading in arc segment is increasing.According to the traditional coal cutting technology,the phenomena of the shearer’s "cutting floor and remaining roof’ will appeared when the shearer is"downhill" from inclined liner section to arc segment.As the curvature of the arc segment increases,the AFC is suspended and the supports of arc section are squeezed.After the effect of coal loading deteriorates due to curvature and position change of AFC,it further provides negative feedback on the stability of the R-S-F system.After repeated vicious cycles,the complexity of support system of the arc segment reappears.For this reason,it is necessary to ensure the curvature of the arc segment to achieve normal advancement of the working face.In view of the complexity of the coal cutting technology at the arc segment,"cutting roof and remaining floor" is employed to ensure the curvature of the arc segment in field.However,due to the chaos,fuzziness and nonlinearity of coal cuttinging system in steeply dipping seam,it is difficult to determine the value and location of "cutting roof and remaining floor".This paper is based on the occurrence characteristics and production technology conditions of the 37220 sub-level working face in Dongxia coal mine.Through the theoretical analysis,the complexity of the coal cutting and coal loading system in the arc section is found.Taking into account the operating characteristics of the shearer’s road wheel meshing with the pin row in the arc segment,CAD drawing software is employed to quantify the complexity of coal cutting by shearer in arc segment.At the same time,the 3D discrete element numerical calculation software PFC3D is employed to study the complexity of the coal loading in arc section of working face in steeplydipping seam.Finally,the main influencing factors of coal cutting and coal loading in arc section of steeply dipping seam are analyzed and optimized.The main research results are as follows:(1)The chaos,fuzziness and nonlinearity of coal cuttinging system in longwall strick fully mechanized working face in steeply dipping seam,making the field operati-on and scientific research difficult.Its complexity is mainly reflected as follows:The traditional coal-cutting method is dissimilated due to the increase of inclination angle;Poor overall adaptability of equipment;The nonlinear variation of coal cutting track caused by Floating coal accumulation and the layout of Face.(2)Cutting at the arc section employing a traditional cutting technology in straight-line working face,the consequences brought are not only "cutting roof" or "remain floor".The real condition is the effect way of the shearer on the shape of the working face constantly "update".The main factors affecting this process are the longitudinal maximum angle between the chutes,the distance between the two meshing point ofshearer’s walking wheel and the pin row,and the horizontal distance between the axis of the drum.(3)Among the main influencing factors of the coal cutting technology,the longitudinal maximum angle between the chutes essentially determines the "base line" of the nonlinear working face shape.The distance between the two meshing point of shearer’s walking wheel and the pin row mainly determines the operating status of the shearer.The horizontal distance between the axis of the drum determines the "amplitude" of cutting floor and remaining roof,and the location of the slope changing point of the arc segment.(4)Using the three-dimensional discrete element software PFC3D,represented by the"slant-arc-horizontal" layout,the quantitative analysis of the complexity of the coal loading system in longwall strick fully mechanized working face in steeply dipping seam was carried out.It is concluded that as the dip increases,the velocity of coal flow decreases progressively along the axial direction of the drum.The non-linear arrangement of the working face leads to a new coal loading complexity in an area with smaller dip.