非静水压力条件下巷道围岩破碎区应力分布特征

Study on stress distribution characteristics of roadway surrounding rock damaged zone under non-hydrostatic pressure

  • 摘要: 煤矿巷道围岩的应力状态与稳定性关系密切,巷道围岩破碎区的分布范围及应力分布特征的研究,对于确定巷道支护方案,提高巷道围岩稳定性具有重要的理论意义和工程指导价值。以非静水压力条件下圆形巷道围岩破碎区分布范围为研究对象,建立了非静水压力条件下巷道围岩应力状态分析的力学模型,给出了非静水压力条件下圆形巷道围岩破碎区及塑性区的应力与位移的解析解,对比分析了2者随埋深及侧压系数的变化特征。以大兴煤矿北二采区902工作面运输巷道为工程背景,通过数值分析和理论计算,对比分析了巷道围岩破碎区的应力与位移随埋深及侧压系数的变化特征,评价了围岩稳定性。研究结果表明:在巷道掘进后围岩环向正应力的变化明显比径向正应力剧烈,围岩破坏的主要形式是沿纵向开裂;由于不同区域的围岩变形特征不同,使其黏聚力及内摩擦角等物理力学参数的大小存在差异,从而导致围岩破碎区、塑性区和弹性区边界应力产生不连续现象;在一定埋深范围内巷道围岩破碎区及塑性区范围随埋深的增加而线性增大。当巷道埋深较小时,巷道围岩破碎区较小,巷道处于相对稳定的状态。当埋深较大时,巷道左、右两帮处较顶底板更易发生失稳破坏;塑性区及破碎区半径的比值随埋深及侧压系数的增大而减小,且随着埋深的增大,侧压系数对围岩塑性区及破碎区范围的影响程度逐渐减小,当埋深增大到一定程度时,围岩应力状态趋于静水压力状态;当埋深达到1 500 m时,围岩达到了极限平衡状态。

     

    Abstract: The stress state of surrounding rock is closely related to the stability of the surrounding rock of the roadway,which is an important subject for studying the safe mining of deep coal resources,and also an important theoretical basis for studying the optimal design of roadway support.In engineering practice,the surrounding rock of the roadway has the characteristics of non uniformity.Therefore the research on the stress distribution characteristics of the surrounding rock under the condition of non hydrostatic pressure has theoretical significance and engineering guidance value.Taking the variation of the surrounding rock stress and displacement in circular roadway as the research object,the theoretical calculation model under the condition of non hydrostatic pressure was established,and the stress and displacement of the surrounding rock damaged zone and plastic zone of circular roadway under non hydrostatic pressure were given.Taking the 902 working face haulage roadway in the north 2nd mining area of Daxing Coal Mine as an example,the characteristics of the stress and displacement of the surrounding rock damaged zone and plastic zone with the buried depth and lateral pressure coefficient were compared and analyzed,and the numerical analysis was applied.The numerical excavation model of circular roadway was established,and the variation of the damaged zone of surrounding rock under roadway excavation under different buried depth conditions was simulated.The numerical results were compared with theoretical calculations to evaluate the stability of surrounding rock.The results show that the change of surrounding rock normal stress is more severe than radial normal stress after tunnel excavation,which shows that the main form of surrounding rock failure is along the longitudinal crack.Due to the different deformation characteristics of surrounding rock in different areas,the values of the physical and mechanical parameters such as cohesion and internal friction angle are different,which lead to the discontinuity of the surrounding rock boundary stress.When the roadway is buried,the radius of the damaged zone and the plastic zone increases linearly with the increase of the buried depth in a certain depth.When the depth is small,the surrounding rock crushing area of the roadway is small,and the roadway is in a relatively stable state.When the buried depth is large,the left and right gangs of the roadway are more susceptible to instability and damage than the top and bottom of the roadway.The ratio of the radius of the plastic zone and the damaged zone decreases with the increase of buried depth and lateral pressure coefficient,and with the depth of buried increasing,the influence of the lateral pressure coefficient on the plastic zone and the damaged zone of the surrounding rock gradually decreases.When the buried depth increases to a certain extent,the stress state of the surrounding rock tends to a hydrostatic pressure state;the surrounding rock reaches the limit equilibrium state when the buried depth reaches 1 500 m.

     

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