考虑轴向应力作用的巷道偏应力分布与破坏特征关系

Relationship between deviatoric stress distribution and failure characteristics of roadway considering axial stress

  • 摘要: 通过理论分析建立了考虑巷道轴向应力影响的全平面应变问题三维模型,推导了三维应力场下巷道围岩第二不变偏应力J2隐式解析解,分析了巷道围岩在弹性状态和塑性状态时不同水平侧压和轴向侧压应力环境下的J2分布大小及形态演化规律。基于Kastner求解法得出了三维应力场下的巷道围岩塑性区边界隐式解,并运用数学与数值分析方法研究了不同应力条件下巷道围岩塑性区分布特征。建立了第二不变偏应力J2与围岩塑性区形态的相互对应关系,揭示了巷道围岩的变形破坏机制。以寸草塔二矿31205工作面回风巷为工程背景,对叠加采动作用下的巷道围岩J2及塑性区分布特征展开研究,量化了非对称变形破坏特征,寻求了支护阻力与J2的相互作用关系,提出了叠加采动巷道的稳定性控制技术。研究结果表明:固定轴向侧压值变化水平侧压值的情况下,J2和塑性区形态分布特征呈现“圆形−类椭圆形−类蝶形”的演化过程。固定水平侧压值变化轴向侧压值的情况下,J2和塑性区形态保持不变。轴向应力的改变对塑性区形态的影响较小,但会对塑性区尺寸产生较大影响。巷道围岩J2的集中程度越大,围岩的变形破坏程度越大,J2的分布形态一定程度上决定了塑性区的破坏形态。31205回风巷在叠加采动影响下处于高偏应力J2环境,且形成了向采空区一侧旋转的应力分布特征,致使巷道形成非对称大变形破坏。支护阻力的提高对巷道围岩的偏应力J2的降低作用有限,仅依靠锚杆(索)无法完全对巷道围岩进行稳定控制。基于上述研究,提出了超前强力支架+锚杆(索)支护系统的组合控制技术,现场应用效果良好。

     

    Abstract: Through theoretical analysis, a three-dimensional model of the full-plane strain problem considering the influence of the axial stress of the roadway is established. The implicit analytical solution of the second invariant deviatoric stress J2 of the roadway surrounding rock under the three-dimensional stress field is derived. The distribution and morphological evolution of J2 under different horizontal lateral pressure and axial lateral pressure stress environments in the elastic state and plastic state of the roadway surrounding rock are analyzed. Based on the Kastner solution method, the implicit solution of the plastic zone boundary of roadway surrounding rock under three-dimensional stress field is obtained, and the distribution characteristics of plastic zone of roadway surrounding rock under different stress conditions are studied by mathematical and numerical analysis methods. The corresponding relationship between the second invariant deviator stress J2 and the plastic zone shape of surrounding rock is established, and the deformation and failure mechanism of surrounding rock is revealed. Taking the return airway of 31205 working face in Cuncaota No.2 Mine as the engineering background, the distribution characteristics of J2 and plastic zone of roadway surrounding rock under superimposed mining are studied, the characteristics of asymmetric deformation and failure are quantified, the interaction relationship between support resistance and J2 is sought, and the stability control technology of superimposed mining roadway is proposed. The results show that: When the axial lateral pressure value is fixed and the horizontal lateral pressure value is changed, the morphological distribution characteristics of J2 and plastic zone show the evolution process of ‘circular-elliptical-butterfly-like’. When the horizontal lateral pressure value is fixed and the axial lateral pressure value is changed, the shape of J2 and plastic zone remains unchanged. The change of axial stress has little effect on the shape of plastic zone, but has a great influence on the size of plastic zone. The greater the concentration of surrounding rock J2, the greater the degree of deformation and failure of surrounding rock. The distribution of J2 determines the failure mode of plastic zone to a certain extent. The 31205 return airway is in a high deviatoric stress J2 environment under the influence of superimposed mining, and the stress distribution characteristics of rotating to the side of the goaf are formed, resulting in the formation of asymmetric large deformation and failure of the roadway. The increase of support resistance has limited effect on the decrease of deviatoric stress J2 of roadway surrounding rock, and it is impossible to completely control the stability of roadway surrounding rock only by bolt ( cable ). Based on the above research, the combined control technology of advanced strong support + bolt ( cable ) support system is proposed, and the field application effect is good.

     

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