孔槽式圆盘破坏特性与裂纹扩展机制颗粒流分析

Particle flow simulation of fracture characteristics and crack propagation mechanism of holed-cracked Brazilian disc specimen

基于室内岩石类脆性材料圆盘试样巴西试验结果,利用颗粒流程序(PFC),获得一组能够反映其力学特征的细观参数。在此基础上,对孔槽式圆盘试样进行巴西试验模拟,分析了裂隙倾角和半径比变化对孔槽式圆盘试样力学参数和裂纹扩展规律的影响。孔槽式圆盘试样力学参数显著低于完整圆盘试样,降幅与孔槽几何参数密切相关。劈裂荷载随裂隙倾角的增大呈非线性变化,而随着半径比的增大呈近似线性减小规律。通过分析认为,在试验模拟范围内保持半径比不变,当裂隙倾角较小时,孔洞是主裂纹起裂的主要诱因;裂隙倾角较大时,裂隙成为主裂纹起裂的主要诱因。保持裂隙倾角不变,当半径比较小时,裂隙是主裂纹起裂的主要诱因;半径比较大时,孔洞成为主裂纹起裂的主要诱因。最后,从细观层面探讨了孔槽式圆盘试样裂纹扩展机制。

Based on the experimental results of intact Brazilian disc of rock-like materials, a set of mecroscopic parameters in particle flow code （PFC） that can reflect the macroscopic mechanical behavior of rock-like materials under Brazilian test are obtained. Then PFC is used to simulate Brazilian test for holed-cracked Brazilian disc （HCBD） specimen. The effect of crack angle and radius ratio on the mechanical parameters of HCBD specimen is analyzed. Compared with intact specimen, the split load of HCBD specimen takes on a reducing tendency, and the reducing extent is closely related to pre-hole and crack parameters. The split load is non-linearly changed as crack angle increasing, but linearly decreases as the increase of radius ratio. In the range of simulation test, when the crack angle is smaller, the hole is the main reason resulting in the main crack initiation;while the crack angle is bigger, the reason of main crack initiation results from the pre-existing crack. When the crack angle is a constant and the radius is relatively smaller, the pre-existing crack is the main reason of main crack initiation;while the crack angle is bigger, the main crack initiation results from the pre-existing hole. Finally, the crack propagation mechanism of HCBD specimen is discussed.