论文标题
岩桥的尺度效应的数值研究
Numerical investigation of the scale effects of rock bridges
论文作者
论文摘要
联合持久性的概念已被广泛用于研究岩石质量的力学和失败过程，从而受益于不连续性的统计线性权衡的简单性。然而，该术语忽略了岩石桥的规模效应，这意味着相同的联合持久性可能指的是岩桥的不同数字和间距，从而导致错误的等效岩体质量反应。为了填补这一空白，完整的岩石桥被分散为多岩桥，同时保持恒定的关节持久性，并通过使用通用不同元素代码（UDEC）进行数值模拟来直接剪切。通过这种方式，从负载置换曲线，压力和位移场，裂纹传播和AE表征的角度研究了岩石桥的比例影响。结果表明，剪切电阻以及应力浓度的面积和价值随着分散体的增加而降低。此外，首先观察到以弧度方式移动和降解的位移场的不均匀分布，这首先观察到了多岩桥的顺序故障。还发现，机翼裂纹的繁殖对尺度不敏感，而宏剪切裂缝的垂直度主要是由于次级裂纹而形成的，随着分散体的增加而降低。此外，岩石桥的分散体的增加将与强烈的AE活动确定的失败前体重叠。基于上述结果，我们评估了现有的方法来表征关节持久性，并观察到可能定义岩石桥的阈值。
The concept of joint persistence has been widely used to study the mechanics and failure processes of rock masses benefitting from the simplicity of statistical linear weighing of the discontinuity. Nevertheless, this term neglects the scale effects of rock bridges, meaning that the same joint persistence may refer to different numbers and spacings of rock bridges, leading to erroneous equivalent rock mass responses. To fill in this gap, an intact rock bridge was dispersed as multi rock bridges while maintaining a constant joint persistence, subjected to direct shear by conducting numerical simulations employing Universal Distinct Element Code (UDEC). In this way, scale effects of rock bridges were investigated from the perspective of load-displacement curves, stress and displacement fields, crack propagations and AE characterizations. Results revealed that the shear resistance and the area and value of stress-concentration decreased with increasing dispersion. Furthermore, uneven distribution of displacement fields in an arc manner moving and degrading away from the load was first observed, indicating the sequential failure of multi rock bridges. It was also found that the propagation of wing cracks was insensitive to scale, while the asperity of macro shear fracture mainly formed by secondary cracks decreased with increasing dispersion. In addition, increasing dispersion of rock bridges would overlap the failure precursors identified by intense AE activities. Based on the abovementioned results, we evaluated existing methods to characterize the joint persistence, and a threshold was observed to possibly define a rock bridge.
