Research On Key Parameters And Surrounding Rock Control Of No Gateside Pack Top Cutting Pressure-relief Of Gob-side Entry Retaining In Deep Mining

In order to cope with the development trend of the coal industry,improve the coal recovery rate and alleviate the problem of mine mining replacement,the research on no gateside pack top cutting pressure-relief of gob-side entry retaining in deep mining has been continuously developed.By cutting off the mechanical conduction between the roof above the roadway and the roof in the goaf,the stability of the surrounding rock can be effectively maintained.The optimum selection of the key parameters such as cutting top height,cutting top Angle directly determines the top cutting pressure-relief effect.This paper adopts Huaibei Hengyuan coal mine Ⅱ 632 fully-mechanized working face as the research background.I use the three-dimensional physical analog simulation,UDEC numerical simulation,theoretical model analysis and engineering verification to study key parameters of the top cutting height and top cutting angle.The paper puts forward the reasonable principle of surrounding rock control and gets good effect.The research content and achievements of this paper can be elaborated from the following aspects:(1)UDEC discrete element numerical simulation is used to study the key parameters of top cutting pressure-relief under different surrounding rock conditions.Model adopts the method controlling variable to study the effect of different mining height,top cutting height and top cutting angles.The regular of Ⅱ632 fully-mechanized working face stress field and displacement field of roadway under different mining height and different cutting parameters will be studied..(2)Three-dimensional similarity simulation experiment uses 1:100 roadway model reproduces Ⅱ632 fully-mechanized working face.The experiment researchs no gateside pack top cutting pressure-relief of gob-side entry retaining in first excavation and excavation stability of roadway surrounding rock.I use close shot photos and strain monitoring technology to observe model’s displacement and stress changes from two angles.The stratascope monitors the internal changes of surrounding rock in roadway.Through the analysis of the data collected in the three-dimensional similarity experiment,the surrounding rock deformation is mainly in the vertical direction.And the amount of deformation on roadsides is small.Therefore,By cutting off the mechanical conduction between the roof above the roadway and the roof in the goaf,the stability of the surrounding rock can be effectively maintained.(3)This paper discusses the influence of the roadway of surrounding rock in deep mine,I classify the roof of coal seam condition level,and divides roof into stable roof structure,easier stable roof structure,hard stable roof structure and difficult stable roof structure according to the evaluation strength of caving zone and criterion of hard rock in fracture zone.This paper establishs the mechanical model of the hard stable structure and analyzes the cutting top height and cutting top angle.I finally present the calculation formulas of key parameters.(4)Based on theoretical analysis,numerical simulation and physical analog simulation experiment results of no gateside pack top cutting pressure-relief of gob-side entry retaining in deep mining,the paper put forward the surrounding rock maintenance policy.And through Hengyuan coal mineⅡ632 fully-mechanized working face machine lane conditions,the policy has proved correct.The field observation data can prove that the stress concentration problem of hard stable roof structure can be solved by using the method of top cutting pressure-relief.The no gateside pack of gob-side entry retaining stability can be better maintained and the deformation can be reduced.So Ⅱ632 fully-mechanized working face’s no gateside pack of gob-side entry retaining is successful.Figure [69] Table [6] Reference [93]...