考虑中间主应力和支护力的巷道围岩黏-弹塑性解

    Analytical solution of viscoelastic-plastic of roadway surrounding rock considering intermediate principal stress and supporting force

    • 摘要: 岩石流变特性对巷道围岩的变形具有重要影响,往往会导致围岩发生大变形甚至失稳。为了全面地分析圆形巷道围岩的变形特性,采用流变模型的串联理论,将Burgers模型与统一强度准则下的摩擦片进行组合,得到了一种考虑围岩塑性的黏-弹塑性围岩本构模型。在对围岩进行弹塑性分析时,考虑了中间主应力系数和支护力的影响,并利用非关联流动法则,得到了巷道围岩塑性区半径和位移解析式。结合算例分析了中间主应力和支护力对巷道围岩塑性区半径及其应力场和位移场的影响,以及位移随时间的变化规律。研究结果表明:巷道围岩先后经历减速蠕变和稳速蠕变两个阶段。在减速阶段,围岩的位移增速较大,前期支护压力大。而在稳速阶段,围岩位移增速虽略有减小,但依然需要支护保持稳定;通过增大中间主应力和支护力,可以减小塑性区半径和围岩位移,提高巷道围岩的稳定性。此外,随着时间的增加,围岩变形逐渐增大,而通过增大支护力,可有效抑制围岩发生变形的速度,在一定程度上缓解了围岩变形。

       

      Abstract: The rheological properties of rock have an important influence on the deformation of surrounding rock of roadway, which often leads to large deformation or even instability of surrounding rock. In order to comprehensively analyze the deformation characteristics of surrounding rock of circular roadway, the Burgers model is combined with the friction plate under the unified strength criterion by using the series theory of rheological model, and a viscoelastic-plastic constitutive model of surrounding rock considering the plasticity of surrounding rock is obtained. In the elastic-plastic analysis of surrounding rock, the influence of intermediate principal stress coefficient and supporting force is considered, and the analytical formula of plastic zone radius and displacement of roadway surrounding rock is obtained by using the non-associated flow rule. Combined with an example, the influence of intermediate principal stress and supporting force on the radius of plastic zone, stress field and displacement field of surrounding rock of roadway is analyzed, and the variation law of displacement with time is analyzed. The results show that the surrounding rock of roadway has experienced two stages of deceleration creep and steady creep. In the deceleration stage, the displacement growth rate of surrounding rock is large, and the early support pressure is large. In the steady speed stage, although the growth rate of surrounding rock displacement decreases slightly, it still needs support to maintain stability. By increasing the intermediate principal stress and supporting force, the radius of plastic zone and the displacement of surrounding rock can be reduced, and the stability of surrounding rock of roadway can be improved. In addition, with the increase of time, the deformation of surrounding rock increases gradually. By increasing the supporting force, the deformation speed of surrounding rock can be effectively inhibited, and the deformation of surrounding rock can be alleviated to a certain extent.

       

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