Macroscopic and microscopic shear failure characteristics of anchored penetrating jointed rock mass
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摘要:
为了研究加锚贯通节理岩体的剪切破坏特性，根据室内实验及数值模拟软件PFC2D，分析了不同法向应力及不同锚固角度作用下，加锚贯通节理岩体的抗剪性能及内部细观裂纹的演变过程。研究表明：（1）随着锚固倾角的增加，加锚节理岩体抗剪强度呈现先增大后减小的趋势，且在锚固角度为60°时，其抗剪强度最大，锚固效果最好。随着法向应力越大，加锚节理岩体抗剪强度越高，其抗剪性能越好。（2）随着剪切位移的不断增加，由初期阶段在锚杆和节理附近产生的少量裂纹通过不断的向外扩展，最终在锚杆和节理交界处聚集了大量的裂纹，其中裂纹以张拉裂纹为主。（3）锚固角度及法向应力对裂纹扩展影响显著，随着法向应力的增加，裂纹数也呈现了增加的趋势，且岩体破坏越严重。随着锚固角度的变化，加锚节理岩体破坏时形成的裂纹数量有先减小后增大的趋势，且在锚固角度为60°时，产生的裂纹最少。
Abstract:In order to study the shear failure characteristics of anchored jointed rock mass, according to the indoor test and particle flow software PFC2D, the shear behavior and internal meso-crack evolution of the anchored rock mass under different normal stresses and different anchoring angles are analyzed. The researches show that: (1) With the increasing of the anchoring angle, the shear strength of the anchored rock mass increases first and then decreases, and when the anchoring angle is 60°, the shear strength is the largest and the anchoring effect is the best. With the higher the normal stress, the higher the shear strength of the anchored jointed rock mass, the better the shear resistance. (2) As the shear displacement increasing, a small number of cracks generated in the early stage near the anchor and joints, through continuous outward expansion, eventually gather a large number of cracks at the joint between the anchor and the joint, where in the crack, the tensile crack is dominant. (3) The anchoring angle and normal stress have a significant influence on crack propagation. With the increasing of normal stress, the number of cracks also shows an increasing trend, and the rock mass damage is more serious. With the change of the anchoring angle, the number of cracks formed when the anchored rock mass is destroyed firstly decreases and then increases, and when the anchoring angle is 60°, the cracks are the least.
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Key words:
- anchored jointed rock mass /
- particle flow /
- anchoring angle /
- normal stress /
- mesoscopic crack
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表 1 宏观物理力学参数
Table 1. Macrophysical and mechanical parameters
抗压强度/MPa 泊松比 弹性模量/GPa 内摩擦角/（°） 黏聚力/MPa 10.1 0.3 1.24 36 4.56 
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表 2 加锚岩体数值模型细观参数表
Table 2. Mesoscopic parameter table of numerical model of anchored rock mass
名称 数值 名称 数值 最小粒径 0.5 摩擦因数 1.0 颗粒粒径比 1.4 黏结抗拉强度 30.2 体积密度 1890 黏结抗剪强度 30.2 颗粒模量 5.0 平行黏结模量 4.86 颗粒刚度比 1.8 平行黏结半径因子 1.0
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表 3 不同法向应力的作用下及四种不同锚固角度的加锚节理岩体模型进行直剪试验表
Table 3. Direct shear test results of anchored rock mass models under different normal stresses and four different anchoring angles
试验号 法向应力/MPa 锚固角度/（°） 峰值强度/MPa A1 1 30° 4.210 A2 1 45° 5.568 A3 1 60° 6.210 A4 1 90° 3.982 B1 1.5 30° 4.519 B2 1.5 45° 5.912 B3 1.5 60° 6.586 B4 1.5 90° 4.293 C1 2 30° 4.828 C2 2 45° 6.257 C3 2 60° 6.962 C4 2 90° 4.605
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表 4 不同剪切位移处剪切裂纹数、张拉裂纹数及裂纹总数表
Table 4. Number of shear cracks, number of tensile cracks and total number of cracks at different shear displacements
剪切位移/mm 剪切裂纹数 张拉裂纹数 裂纹总数 0.457 23 24 47 1.052 46 181 227 1.657 78 330 408 2.459 108 530 638 3.000 125 790 915
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