Floor Heave Control Of Gob-side Entry In Tongfa Dongzhouyao Colliery

Based on Tongfa Dongzhouyao colliery 5103 gob-side entry production geological conditions,through physical and mechanical experiments,theoretical analysis and numerical simulation,make a deep research on the gob-side entry floor heave mechanism and control method under the influence of mining.Through theoretical calculation and numerical simulation,the width of the stress reduction zone after the goaf is stabilized is analyzed.Considering the design width of 5103 gob-side entry and the chamber situation,the coal pillar width is finally determined to be 6m.Using the suspension theory and limit equilibrium theory to calculate the roadway bolt-mesh cable support parameters,combined with engineering analogy method and tunnel geological conditions,the final determination of 5103 small coal pillar gob-side entry support parameters,The roof and Small coal pillar side is mainly supported by anchor cable.The deformation law of5103 roadway surrounding rock under the original support condition is observed and analyzed:The deformation of top and floor is greater than that of two sides under the influence of working face mining.The deformation of top and floor is mainly floor heave,and the deformation of two sides is mainly represented by deformation of small pillar side.The accumulative floor heave is 600mm,which has seriously affected workers walking and material transport.Based on the structural model analysis of overlying strata in gob-side roadway,the key rock B₂rotates twice under the action of superimposed abutment pressure,and the advance abutment pressure at the top is transferred to the bottom plate by the two sides.The floor strata sliding mechanical model was established,the stress is transferred to the passive stress zone through the floor transition zone,and the roadway floor is uplifted upward,resulting in floor heave.Under the horizontal stress of mining,buckling and instantaneous dilatancy occurred in the floor after broken layer separation.The floor heave of 5103 roadway belongs to the combination of extrusion flow floor heave and flexural fold floor heave.Based on the above analysis,the floor heave control technology of 5103 goaf excavation is proposed,the plan of installing base angle bolt is adopted to effectively control the floor heave.Through the calculation of bolt support strength,the base angle bolt is selectedφ22mm BHR500left rotation steel bolt without longitudinal bars.FLAC^3Dnumerical simulation software is used to analyze the Angle and length of the base angle bolt.Considering the control effect and economy,the base angle bolt can be selected as 2.4m in length and 30°in installation Angle.Based on the background of 5103 roadway,the field industrial test was carried out,and the base angle bolt was installed on the base of the original supporting parameters.The roadway surface displacement was monitored on the 150m away from the beginning of the test,and the floor heave was 240mm.The floor heave was effectively controlled,floor heave is effectively controlled,which indicates that floor heave control technology is feasible and has important guiding significance for floor heave control of gob-side excavation under the same geological conditions.