Research On The Occurrence Law Of Rock Pressure Over The Collapsed Pillar In The Working Face Under The Condition Of Composite Roof

The composite roof is common in the coal-measure strata of the layered sedimentary rock,and accounts for a relatively large proportion of the total coal seams in my country.Its destruction mechanism is complex,which affects the efficient and safe mining of the working face.In addition,there are collapse columns in front of the working face,and the interior is complex and complicated.It is relatively loose and superimposed on the mining stress of the working face,which greatly increases the complexity of the problem and affects the safe production of coal mines.Based on the site conditions of the 9108 working face of Changshun Coal Mine,this thesis uses theoretical analysis,numerical simulation,similar simulation and on-site industrial test methods to study the behavior of mining pressure when the working face passes through the collapse column under the condition of composite roof.The main research results are as follows :(1)The theoretical analysis results show that the collapse column is mainly divided into four areas from the inside to the outside;the limit span of the composite roof and its periodic pressing step will decrease correspondingly as the distance from the collapse column decreases;the collapse column is affected The main causes of internal and external stress changes are the weight of the collapsed column and the stress of the surrounding rock.(2)Numerical simulation analysis results show that: the composite roof is mainly damaged by tension;the stress distribution of the working face past the collapsed column includes four stress stages: stress rise stage,abnormal stress rise stage,stress reduction stage,and second stress rise stage.(3)Similar simulation analysis results show that tensile failure is the main failure form in the fracture process of the composite roof;the closer the working face is to the collapse column,the smaller the pressing step,the more frequent the cycle pressing,and the farther away from the collapse column.Compression step distance will be appropriately increased,and compression cycle will be appropriately longer.(4)On-site industrial experiment results show that: ZZ13000-21/42 type support has good applicability;reinforcement should be carried out in advance when the working face passes through the collapsed column.Similarly,the supporting pillars,grouting in the coal pillars,and speeding up the working face Methods such as advancing speed and quickly pushing through the area affected by the collapse column can also improve the stability of the coal column ahead.The research results of this paper aim to provide technical reference for safe and efficient mining of Changshun Coal Mine 9108 face,provide theoretical basis for its safe and efficient mining and safe passage through collapse column,and provide guidance for similar face mining in Yuxian area..