应力波作用下煤岩层面超低摩擦特征解析理论研究

Analytical theoretical study on ultra-low friction characteristics of coal rock interfaces under stress wave action

  • 摘要: 在地质构造、开挖面切割以及高应力、强采动影响下,深部煤岩大多具有明显的块状构造特征,当受到顶板断裂等动载应力波作用下时,这些块状煤岩层面极有可能会产生超低摩擦滑动现象,进而诱发滑移型冲击地压等动力灾害事故。为了探究应力波作用下煤岩层面超低摩擦特征,基于应力波传播理论推导了应力波与煤岩层面相互作用解析理论模型。在解析模型中,分别采用Bandis-Barton模型以及Coulomb-slip模型表征煤岩层面的法向和切向行为。通过将解析模型与已有理论模型以及相同的UDEC模型计算结果进行比较,验证了解析模型的可靠性。讨论了煤岩层阻抗比、煤层高度、应力波入射角对应力波作用下煤岩层面超低摩擦特征的影响。研究结果表明:随着煤岩层波阻抗比的增加,煤岩层面相对法向位移的变化范围越大,煤岩层面越容易产生超低摩擦现象,或更容易产生摩擦力更小的现象;煤层高度越高,煤岩层面的相对法向位移变化以及相对切向位移变化整体上越小,煤岩层面整体上越不容易产生超低摩擦现象;随着应力波入射角(10° ~ 40°)的增加,煤岩层面相对法向位移的变化范围越小,但煤岩层面的切向应力分量变化增大,若没有水平推力作用,随着应力波入射角的增加,煤岩层面发生超低摩擦滑动的可能性更大。

     

    Abstract: Under the influence of geological structure, excavation surface cutting, high stress, and strong mining, deep coal and rock mostly have obvious block-like structural characteristics. When subjected to dynamic stress waves such as roof fracture, these block-like coal rock interfaces are highly likely to induce an ultra-low friction sliding phenomena, leading to slip-type coal burst and other dynamic disasters. In order to explore the ultra-low friction characteristics of coal rock interfaces under the action of stress waves, an analytical theoretical model for the interaction between stress wave propagation and coal rock interfaces was derived based on the theory of stress wave propagation. In the analytical model, the Bandis-Barton model and Coulomb-slip model were used to characterize the normal and tangential behaviors of the coal rock interfaces, respectively. The reliability of the analytical model was verified by comparing its calculation results with existing theoretical models and the same UDEC model. The influence parameters such as the impedance ratio of coal rock layers, coal seam height, and the incident angle of stress waves on the ultra-low friction characteristics of coal rock interfaces under the action of stress waves was discussed. The research results indicate that as the impedance ratio of coal rock layers increases, the change range of relative normal displacement of coal rock interfaces becomes larger, and the coal rock interfaces are more prone to an ultra-low friction or lower friction. The higher the height of the coal seam, the smaller the overall changes in the relative normal displacement and relative tangential displacement of the coal rock interfaces, and the less likely the coal rock interfaces is to induce an ultra-low friction. With the increases of the incident angle of stress waves (10° ~ 40°), the change range of relative normal displacement of the coal rock interfaces decreases, but the tangential stress component of the coal rock interfaces increases. Without horizontal thrust, the possibility of ultra-low friction sliding on the coal rock interfaces is greater as the increase of incident angle of stress waves.

     

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