近距离煤层工作面煤柱合理留设与巷道围岩控制技术

Reasonable coal pillar setting and roadway surrounding rock control technology in close-distance coal seam working face

  • 摘要: 为探究近距离煤层工作面煤柱合理留设宽度以及回采巷道围岩控制技术,以回坡底煤矿近距离煤层开采为工程背景,通过数值模拟、理论分析、现场实践等技术手段对不同宽度条件下煤柱破坏演化过程、影响因素、底板破坏范围以及11号煤层回采巷道围岩控制技术进行了深入研究。研究结果表明:(1)煤柱在预留煤柱时期、区段煤柱时期、保护煤柱时期、孤岛煤柱时期四个阶段过程中,煤柱破坏范围逐渐增大;煤柱弹性核占比均随煤柱宽度的增加而增加,本煤层回采巷道随煤柱宽度的增加从非对称性破坏逐渐演化为对称性破坏。煤柱破坏宽度与煤层倾角、黏聚力、煤柱宽度、内摩擦角和泊松比等因素成反比关系,只与埋深成正比关系。(2)随着煤柱宽度增大,煤柱底板破坏宽度与深度会发生变化,且底板破坏集中在煤柱边缘侧,煤柱正下方底板破坏区域较小。(3)煤柱应力集中作用致底板下方最大主应力发生偏转,底板任意一点与煤柱中心线的距离越大,最大主应力偏转角度越小;随着11号煤层巷道与煤柱边缘距离的增大,巷道围岩塑性区由倾斜的“X”形分布转变为倾斜的“8”形分布,再转化为倾斜的“O”形分布,最终转化为椭圆形分布;离煤柱距离较近时,巷道往往出现非对称性破坏,支护也要采取非对称支护形式。

     

    Abstract: To explore the reasonable width of the coal pillar and surrounding rock control technology of the mining roadway in a close-distance coal seam working face, this paper took the mining of No.10 and No.11 coal seams of the Huipodi coal mine as the engineering background. Through numerical simulation, theoretical analysis, field practice, and other technical means, the evolution of the coal pillar failure, influencing factors, and damage range of floor under different widths were analyzed. The surrounding rock control technology of the mining roadway was studied in depth. Results show that: (1) During the four stages of reserved, section, protective, and isolated coal pillars, the damage scope of the coal pillar gradually increased. The proportion of the elastic core of the coal pillar increased with the increase of the coal pillar width. The mining roadway in this coal seam evolves from asymmetric failure to symmetrical failure. The failure width of the coal pillar is directly proportional to the buried depth and inversely proportional to the coal seam dip angle, cohesion, coal pillar width, internal friction angle, and Poisson’s ratio. (2) With the increase in coal pillar width, the width and depth of the coal pillar floor failure will change. Moreover, the floor failure concentrated on the side of the coal pillar edge, and the damaged floor area under the coal pillar is observed to be small. (3) The maximum principal stress under the floor deflects owing to the concentrated stress of the coal pillar. The larger is the distance between any point of the floor and the centerline of the coal pillar, the smaller is the deflection angle of the maximum principal stress. With the increase in the distance between the roadway and coal pillar edge, the plastic zone of the roadway surrounding rock initially changes from an inclined X-shaped distribution to an inclined 8-shaped distribution, which then changes to an inclined O-shaped distribution and finally to an elliptical distribution. When the distance from the coal pillar is close, the roadway often shows an asymmetric failure, and the support should also take the form of asymmetric support.

     

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