Study On The Stability And Engineering Application Of Coal Columns Between Mining Surfaces

At present,in the long-wall mining of underground coal,In order to protect the mining roadway,coal pillar is mainly used between the mining faces to insulate the impact of mining.How to design safe,reliable and economical coal pillar is very important in the design process.In order to study the stability of coal pillar between the mining faces and give the design m ethod of reasonable width of coal pillar,adopted the methods of field monitoring,theoretical derivation and numerical simulation,this paper studies the load of coal pillar,the bearing pressure distribution of coal pillar,and the plastic failure zone of coal pillar,applied the results to the design of coal pillar between the mining faces of Yuhua coal mine.The research mainly includes the following four aspects:(1)In terms of the load on the coal pillar,considering that the bearing capacity of the caving rock mass in the goaf can not be ignored after coal mining when the inclined length of the working face is larger.Therefore,based on the analysis results of the load data of the coal pillar,the force transfer arch model under the influence of mining is established to revealing the load transfer mechanism of goaf-coal pillar and determining the load bearing capacity of caving coal and rock in goaf.The theoretical calculation method of load on coal pillar between mining faces is given.The results show that the overburden load in the goaf is shared by the caving coal rock mass and the force transfer arch in the goaf,and the load of the caving coal rock mass in the goaf can be expressed by the product of the compression modulus and the compression deformation of the caving coal rock mass,and the load of the transfer arch is transferred to the coal pillar through the arch foot.(2)In the aspect of coal pillar stability,By building a coal pillar stress model and combining with elasto-plastic theory,the influence range of coal pillar's mining action,the distribution of pillar's supporting pressure and plastic failure zone,the location of roadway,the width of coal pillar's retaining and the way of strengthening coal pillar are analyzed.The influence of the parameters on the width of the coal pillar and the width of the plastic failure zone of the coal pillar is analyzed.(3)According to the actual working condition of Yuhua coal mine in Tongchuan Jiaoping mining area of Shaanxi Province,combined with the physical and mechanical properties test data of indoor coal and rock body,the coal pillar between mining faces with a buried depth of 580 m,inclined length of 240 m is designed in detail,The reasonable width of coal pillar and the width of plastic zone under different buried depth and inclined length of working face are given,which provides theoretical suggestion value for selecting the remaining width of coal pillar in the next stage of production of Yuhua Coal Mine.(4)The applicability and rationality of the coal pillar design method in this paper are studied by numerical simulation.Comparison of numerical and theoretical results,It is found that this theory is suitable for medium mining height in the calculation of plastic failure zone of coal pillar(4?7 m);In terms of the width of the pillar,the width of the elastic core area of the pillar can reach 2 times the height of the pillar,and the width of the pillar can meet the design requirements.