Study on the evolution law of bottom plate stress and reasonable roadway misalignment in downstream mining of coal seam group
In order to solve the problem of reasonable arrangement of the roadway under the residual coal pillar in close distance coal seam mining,the mechanical model of stress distribution of rock layer under the residual coal pillar was established based on the semi-infinite planar body theory by theoreti-cal analysis,numerical simulation and on-site measurement,and the stress distribution of bottom plate rock layer under the residual coal pillar and the relative position of decompression zone were systemati-cally studied,so as to put forward a method of determining the bottom plate horizontal/vertical distance under the influence of uneven load,revealing the influence of horizontal/vertical spacing on the rate of stress change of the residual pillar.The results show that the vertical stress concentration is the main control factor leading to the instability of the downfall roadway,and the vertical stress change of 0.2γH is used as the critical index for judging the degree of stress influence,and the degree of stress perturba-tion under the influence of different mining factors is investigated,and with the gradual decrease in the size of residual coal pillar,spacing of the coal seams,and the depth of burial and the angle of rock col-lapse,the depth of stress influence on bottom plate rock layer shows a decreasing tendency;and with the increase of the horizontal misalignment distance,the vertical stress value,stress value and stress value of the surrounding rock are decreased,and with the increase of the horizontal misalignment dis-tance,the depth of stress influence is increased.With the increase of horizontal misalignment,the verti-cal stress value of the surrounding rock and the difference of stress change rate decreases,and the sur-rounding rock reaches a controllable and stable state when defining the two values lower than 0.2γH and 0.01;the field test 21320 backwind lane adopts external misalignment of 25 m for the measure-ment verification,and the relative displacement of the roof plate after the optimization arrangement of the roadway is controlled to be less than 45 mm,and the surrounding rock of the roadway is in stable condition during the service period,which verifies the reasonability of the obtained safety misalign-ment.
万方数据
维普
