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煤巷围岩应力分布特征及帮部破坏机理研究

Study on surrounding rock stress distribution characteristics andsidewall failure mechanism of seam gateway

  • 摘要: 为探究煤巷开挖围岩应力分布特征,并基于此分析巷帮破坏机制及其影响因素,采用数值试验研究手段分析了煤巷开挖围岩垂直与水平应力分布规律及巷帮高度的影响,围岩应力变化全过程;构建了开挖卸荷应力路径下巷帮破坏机制理论模型,将受卸荷应力作用的巷帮煤体分为破裂区、塑性区及弹性区,推导了巷帮煤体破裂区及塑性区应力、破裂区宽度、非弹性区范围及水平位移的解析表达式。研究结果表明:开挖将导致巷帮一定范围内煤体所受垂直应力增加,水平应力不断降低,二者之间差值不断加大,围岩逐渐由三向受压变为只有两向受压,应力平衡状态被打破,变形破坏将会发生;应用高预应力强力锚杆支护后,能够在巷道围岩内部产生一定范围压应力场,巷帮煤体又逐渐恢复到三向受压状态。经工程实例验证可知,在一定范围内提高支护强度,能够降低巷帮变形破坏程度,但影响逐渐减弱。

     

    Abstract: In order to study the stress distribution features of the excavated surrounding rock in the mine seam gateway and based on the analysis on the failure mechanism and the influence factors of the seam gateway sidewalls, a numerical experiment study means was applied to analyze the vertical and horizontal stress distribution law of the excavated surrounding rock in the mine seam gateway and the height influences of the gateway sidewalls and to analyze the full stress variation process of the surrounding rock. A failure mechanism theoretical model of the seam gateway sidewalls under the excavation unloading stress path was established. The coal mass of the seam gateway sidewalls affected by the unloaded stress role was divided to a creaking zone, plastic zone and elastic zone. An analytic expression of the creaking zone in the coal mass of the gateway sidewalls and the stress in the plastic zone, width of the creaking zone, scope of the non elastic zone and the horizontal displacement value was derived. The study results showed that the excavation would cause the vertical stress increased on the coal mass within a certain scope of the gateway sidewalls, the horizontal stress would be continuously decreased and the difference between the two stresses would be continuously increased. The surrounding rock would be pressed from the three dimensions to the two dimensions, the stress balance status would be broken and the deformation failure would be occurred. With the application of the high pre-stressed powerful bolt support, a pressure stress field with a certain scope would be occurred in the surrounding rock of the seam gateway and the three dimension pressurized status of the coal mass in the gateway sidewalls would be recovered steadily.The engineering cases verified that the support intensity increased within a certain scope could reduce the deformation failure degree of the gateway sidewalls, but the influences would be steadily reduced.

     

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