Study On Reasonable Size Of Coal Pillar In Working Face Section Of Banglaiwan Coal Mine

As the protective pillar of the safe passage of the working face,the rationality of the reserved width of the coal pillar in the fully mechanized working face is not only related to the safety and stability of the working face along the trough,but also related to the improvement of the recovery rate of the mine,which is one of the problems restricting the safe and efficient production of the coal mine.If the coal pillar is too large,it is easy to cause waste of coal resources.If the coal pillar is too small,the coal pillar can not play the role of supporting load.The working face is prone to deformation and damage along the trough,which will cause water and harmfull gas leakage in the goaf.Based on the above phenomena,the paper combined with the current situation of the pillar reservation in the comprehensive mining face of hanglaiwan coal mine,carried out the research on the optimization and stability of the pillar width in hanglaiwan coal mine,and the research results will provide scientific basis for the safe and efficient mining and the subsequent support optimization.The thesis adopts a comprehensive research method combining laboratory experiments,theoretical analysis,numerical calculations,and on-site monitoring,and measures the physical and mechanical parameters of roadways and coal pillars through laboratoory experiments of mechanical properties of coal rocks;With the help of the mechanical model of the elastic zone of the coal pillar,the stress distribution law of the coal pillar,the stability characteristics of the roadway and coal pillar,and the factors affecting the stability are analyzed.The SMP criterion is used to determine the width of the plastic zone at the side of the coal pillar goaf is 1.3 m,the w idth of the plastic zone on the side of the roadway is 5.2m,and the width of the elastic zone is 5m.Finally,the reasonable theoretical width,of the coal pillar in the section is determined to be 16m;Based on laboratory tests and theoretical analysis calculations,FLAC3D numerical calculation software is used to establish a numerical model of coal pillars in a section,and the widths of coal pillar plastic zones and stress distribution surrounding rocks are analyzed during the tunneling of different width sections and the mining of both working faces Displacement and support pressure distribution characteristics determine the reasonable optimized width of the coal pillar.It is concluded that when the coal pillar is reduced to 16m,there is still a certain elastic area inside the coal pillar.The simulation results are consistent with the theoretical calculation results;The borehole stress gauge,optical borescope,and“cross-point method" were used to verify the stability of the coal pillar in the 16m section.The results show that the working area's leading influence range is approximately 40-50m,regardless of the area.The section of coal pillar is affected by mining on one side or mining on both sides.The middle part of the coal pillar still has an elastic zone of over 5m,and the convergence of the roadway is in a controllable range.During the production process,the roadway has no gangs or roofs.The bottom plate is sinking and bottoming.The research results of this paper not only have guiding significance for the optimization of coal pillars in the follow-up working face section of hanglaiwan coal mine,but also provide a basis for the reasonable optimization of coal pillar width and stability analysis in the large mining height working face section.