Study On Roadway Floor Impact In Coal Mine

In order to improve the theory and technology level of floor rock burst prevention and control in Yima mining area,and reduce the occurrence and damage degree of coal gangue interbedded floor rock burst disaster.Taking the overlapping floor rock burst mine in Yima Coal Mine of Henan Province as an example,the stress distribution model of roadway floor was constructed by theoretical analysis.Through similar simulation experiment,the influence law of ’soft-hard-soft ’ three-layer overlapping floor on roadway floor impact in coal pillar island working face was explored.Numerical simulation was used to explore the influence of tunneling speed,coal pillar width,different floor rock combination,different floor rock thickness ratio and bottom coal thickness on roadway floor impact.The influence law of different influencing factors on roadway rock burst is discussed.The main research work of this paper is as follows:(1)Taking the isolated working face of MZ21010 coal pillar in a mine of Yima as the engineering background,the stress distribution model of roadway floor was constructed,and the range of plastic zone in goaf side and roadway side,the vertical stress distribution law of coal pillar,and the vertical stress distribution law of floor under the action of coal pillar were obtained.Based on the theory of material mechanics,the calculation model of horizontal stress of bending moment of roadway floor is constructed,and the minimum horizontal stress Fer of instability failure of floor is obtained.The critical value of horizontal stress of instability failure of floor is related to the strength of floor rock(rock combination strength,rock layer thickness ratio).(2)The similar simulation experiment of ’ soft-hard-soft ’ three-layer overlapping floor in coal pillar island working face was designed to explore the displacement and stress variation of overlapping floor in coal pillar island working face.Digital image correlation method and stress monitoring equipment are used to obtain the movement characteristics and displacement nephogram of the overlapping floor in the process of model excavation,the stress variation curve of the overlapping floor in the process of coal seam mining and the variation law of the vertical stress of the coal pillar floor rock.(3)The numerical model of MZ21010 coal pillar isolated island working face was established by FLAC3 D software,and the influence factors of different tunneling speed and reserved coal pillar width on roadway floor impact were simulated and studied.Appropriately increasing the tunneling speed can reduce the displacement of roadway roof and floor and the horizontal stress of floor rock,which can reduce the floor impact risk.According to the plastic zone volume and elastic energy,when the coal pillar width is 30 m,the floor impact risk is low.(4)FLAC3D software was used to simulate and study the influence factors of roadway floor impact under different lithology combination,different rock thickness ratio and different bottom coal thickness.When the floor rock combination is a single carbonaceous mudstone or contains carbonaceous mudstone combination,the displacement and elastic energy of roadway roof and floor and two sides increase;when the thickness of carbonaceous mudstone increases,the impact risk increases;when the bottom coal thickness is 2 m,the horizontal stress,horizontal stress concentration coefficient and elastic energy of roadway floor reach the maximum value.The special coal gangue overlapping structure in Changcun Coal Mine leads to the impact risk in roadway excavation.There are 69 figures,9 tables and 71 references in this paper.