Study On Coal Pillar Load-bearing Characteristics And Gateroad Support In Longwall Top Coal Caving In Changgou Coal Mine

Taking the 15113 intake roadway in Changgou Mine as engineering background,this paper focuses on the research of coal pillar load-bearing characteristics and the roadway driving along the goaf surrounding rock control.This paper analyses the influence of key block length,fracture location of the big structure,and the roadway size on the coal pillar load-bearing characteristics.Apart from that,this paper assesses the influence of coal pillar widths on the roadway surrounding rock deformation and designs the 15113 intake roadway supporting scheme.The main results are as follows.Broken overlying strata of roadway driving along the goaf is studied by theoretical method and main roof key block parameters are determined by theoretical calculation,which provide numerical foundation for establishing UDEC model of the roof big structure.Trigon element is used to establish roadway surrounding rock UDEC numerical model.Influence of key block length on coal pillar and surrounding rock is studied through UDEC numerical model and it is found that before the key block touches the floor,the pillar is affected by rotation angle and vertical stress of key block;after key block touches the floor,key block is in the state of “given deformation”,as the length of the key blocks increases,the pillars improves bearing characteristics.Influence of key block fracture location on coal pillar load-bearing and surrounding rock deformation is studied and it is found that if key block location is on the top of roadway,the stress and deformation will deteriorate greatly,so it is necessary to prevent key block fracture location on the top of roadway.And however,surrounding rock stability will be best if fracture location is on coal body.Influence of roadway size on coal pillar load-bearing and surrounding rock deformation is studied and it is found that too large roadway size is bad for coal pillar and surrounding rock stability,and shear failure of coal pillar goaf side will be more serious.So roadway size should be as small as possible when meets the use requirement.Influence of lateral supporting stress and main roof fracture location is considered when design coal pillar width.The influence of coal pillar width on the pillar failure characteristics,vertical stress distribution and roadway surface deformation is analyzed and the proper coal pillar width is decided to be 8m.At this time,the location of main roof fracture is on the top of coal pillar.Concerned about the fact that roof is breakable and anchor support is liable to failure,anchor cable joint support scheme is adopted and parameters are determined.To avoid asymmetric deformation of roadway,the Support intensity of coal pillar side will be strengthen.Research results are applied to industrial experiment.The location of main roof fracture is on the top of coal pillar according to detection.After the roadway excavation,surface deformation is small and there is no abscission layer in the roof.Cable and anchor support can bear the weight shortly and its stress is within the limit,which all indicate that coal pillar width design and supporting scheme can control the deformation well and the result meets the requirement.