Deformation and failure law of three-soft roadway and width of the coal pillar influenced by adjacent gob
In order to explore the deformation and failure law of roadway surrounding rock under different coal pillar widths during roadway excavation in three-soft coal seam under the influence of adjacent gob,the research methods of theoretical calculation,numerical simulation,physical similarity simulation and field measurement were used to analyze the stress evolution law,plastic failure range and displacement distribution characteristics of roadway surrounding rock under different coal pillar widths with adjacent gob.The results show that the gob-side zone is the main reason for the asymmetric failure after roadway excavation,which increases the angle between the principal stress direction and the vertical direction of the coal pillar,and the stress distribution in the two sides of the roadway is asymmetric,the coal pillar side is greater than the solid coal side.Dominate failure form of the three-soft roadway is shear failure,which mainly occurs in the two sides.With the increase of coal pillar width,the angle between principal stress direction and vertical direction decreases,and the failure degree of roadway surrounding rock decreases.The influence degree of gob-side zone on different positions of the roadway is different.The failure degree of surrounding rock in the middle of roadway is greater than that at the end,and the failure degree of coal pillar side is greater than that of solid coal side.Increasing the coal pillar width has insignificant improvement on the surrounding rock stress and coal pillar failure.According to the field results,when the width of the coal pillar is 20 m,the demand is satisfied for normal maintenance of the roadway.
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