Research On Reasonable Width And Support Technology Of Coal Pillar Considering Arching Effect

Coal pillars play an important role in supporting the upper strata,mining boundaries and section isolation in coal mining activities.Insufficient coal pillar retention will lead to serious deformation of surrounding rocks,increase the difficulty of roadway maintenance,and even cause the surface to bend and sink,buildings and buildings.Inclination and settlement will damage the ecological environment;if the coal pillar is too wide,it will cause a serious waste of coal resources.How to improve the recovery rate under the premise of ensuring the safety and stability of the roadway is a very important issue in the design and production work.In order to explore the force mechanism and reasonable size of the coal pillar in the stope working face and the support method of the roadway after the coal pillar is left,this paper determines the Morphological characteristics and evolution of pressure arches.Combined with the"pressure arch-coal pillar" load transfer model,the distribution law of the coal pillar support pressure and the width of the plastic zone are analyzed,and finally the roadway support optimization scheme is proposed based on the field measurement results.The specific research results are as follows:(1)Combined with the key layers,the calculation method of the three-zone distribution height is given.By analyzing the structural characteristics and formation mechanism of"parabolic arch","flat-top arch" and "special-shaped arch",it is found that the key layer of overburden affects the shape and evolution of the arch structure.The inner and outer boundaries of the pressure arch axis and the influence range are determined.The influence range is related to the excavation length of working face inclination,rock mass cohesion and internal friction angle.(2)From the analysis of the UDEC numerical simulation results,it can be concluded that as the inclination length of the working face continues to advance,the damage range of the overlying rock in the stope becomes larger,and the accumulation of broken gangue in the goaf increases and is gradually compacted.After advancing for a certain length,the arched compression area is obvious.The stope shape tends to be stable,and it is believed that a stable pressure arch structure is formed at this time.The evolution characteristics of the pressure arch are:with the expansion of the working face,the span of the structure expands and arches upward;when it evolves to the position of the hard key layer,the arch no longer develops upward,and the flattening rate increases.(3)Based on the elastic-plastic theory,the theoretical calculation formula of the pressure arch load and the thickness of the arch body is determined.Based on the pressure arch-coal pillar structure model,the calculation formulas of the coal pillar mining influence range and the width of the plastic zone are obtained through analysis,and it is found that the inclination length of the working face has a great influence on the width of the coal pillar;It is large and decreases,and increases with the increase of burial depth.(4)In the aspect of roadway surrounding rock control,combined with on-site monitoring results,the theoretical results were applied to roadway support and coal pillar reinforcement in Yuhua Coal Mine,and a targeted support optimization design method was proposed based on surrounding rock deformation and support principles.