Study On Optimization Of Coal Column Width In The Section Of Double-digging And Two-mining Roadway In Xiaobaodang No.1 Coal Mine

Aiming at the mining of thick the coal seams with extraordinary long work layer and large mining,how to enhance the recovery ratio,and how to minimize the waste of coal resources and realize the secure efficient production of coal shaft,is a topic of continuous research for practitioners in the coal industry.This thesis takes Xiaobaodang No.1 Coal Mine 112203,112204 mining face and its two lanes as the research subject,adopting some approaches such as on-site investigation,theoretical analysis,numerical simulation,engineering application to study the leading abutment pressure,lateral abutment pressure and residual abutment pressure conduction law behind goaf during mining and mining of double-excavation roadway and the influence area range.Besides,the spatial structure of overlying rock above primary and secondary mining coal pillars is analyzed,as the same time the width of coal pillars with the large cross section,long trend and double-entry mining is optimized.The stress concentration of surrounding rock is optimized for dual-entry layout,and it is successfully used for the construction site to realize secure efficient mining of comprehensive mining of coal shaft.This thesis draws the following conclusions:1)The full-cycle pressure transmission characteristics of double-excavation and double-mining roadway were investigated.The study examined the pressure transmission characteristics of the roadway during double-excavation,primary mining,and secondary mining,the pressure transmission law above coal pillar,the plastic zone range of coal pillar,in addition the law of stress evolution of the elastic bearing core region,based on the measured data.The findings demonstrated that the influence range of roadway advance abutment pressure under secondary mining stress is significantly larger than that under primary mining stress,and the plastic zone expands further.2)An analysis is conducted on the characteristics of roof overburden structure evolution influenced by dual mining.By monitoring the deformation scope of roadway surrounding rock and the plastic character of developmented area coverage,it gets a conclusion that the stress disturbance is small during the excavation of double roadway,and the roadway roof is a beam model,and the surrounding rock deformation is small.Based on the "S-R" stability theory of masonry beams,it is concluded that the roof forms an F-shaped structure during primary mining,the deformation and failure of goaf roadway are severe,morever deformation of surrounding rock sharply increased which compared with that during excavation.During secondary mining,a T-shaped structure is formed by the roof on both sides of the coal pillar,leading to severe surrounding rock deformation of the roadway and frequent dynamic pressure occurrences.3)The thesis reveals the stress distribution law of coal pillar at different mining stages and the stress environment theory of retaining surrounding rock,analyzes the stress distribution environment of coal pillar at different mining and mining stages,studies the stability mechanism of coal pillar and retaining surrounding rock,and calculates the reasonable retaining width of coal pillar at the same time,considering the recovery rate of resources,proposes that the reasonable width of coal pillar should not be less than 15 m.4)The simulation results of rational width numerical value of coal pillar in the section of double-entry mining gallery is determined,which show that 15m-20 m reserved coal pillar can effectively reduce the dynamic development of gallery and ensure the adequate bearing capacity of coal pillar in the segment.With the theoretical calculation results integrating,in order to select the coal pillar approximately15m～20m zone,which can not only optimize the surrounding rock stress concentration,but also enhance the resource recovery ratio.5)The engineering application makes the feasibility of the research results are vertified.The law of stress distribution which is measured in the field is line with the research.In the wake of refining coal pillar width in the segment,stress concentration of surrounding rock reflects better than before,in the surrounding rock and deformation of the gallery development the scope of plastic zone are better controlled,which verifies the rationality and feasibility of segment length from 15 to 20 of coal pillar.This thesis has 83 figures,1 tables and 80 references.