Numerical investigations of the failure mechanism evolution of rock-like disc specimens containing unfilled or filled flaws

Abstract

The mechanical responses and ultimate failure patterns of rocks are associated with the failure mechanism evolution. In this study, smoothed particle hydrodynamics (SPH) method with the mixed-mode failure model is proposed to probe into failure mechanism evolutions for disc specimens upon loading. The tensile damage model and the Drucker-Prager model are used to calculate the tensile failure and shear failure of the material, respectively. It is concluded that for flaw-unfilled disc specimens, the crack coalescence mechanism in the rock bridge area is affected by the flaw inclination angle and the material property. Considering disc specimens with filled flaws, the incremental rate of tensile damage grows more rapidly when the disc and filling material have a closer ratio of tensile strength to cohesion, which makes the entire specimen response greater brittleness. Furthermore, with the increasing non-uniformity of filling distribution, the incremental rate of tensile-activated damage decreases and the disc specimen performs more ductile. Besides, the influence of the fillings is greater when the flaw inclination angle is approaching 45°. It is proved that the proposed SPH method can be used to simulate the failure mechanism evolution of rocks, which lays a foundation for the study of more complex rock failure.

摘要

目的

岩石的力学响应和最终破坏模式与破坏机制的演化有关。本文旨在通过光滑粒子流体力学(SPH)方法模拟材料混合破坏行为, 探讨含填充及未填充裂缝的类岩圆盘试件加载后的破坏机制演变。

创新点

1. 在SPH框架中引入混合破坏模型模拟类岩圆盘试样的破坏行为; 2. 通过SPH数值模拟方法分析圆盘试样的破坏机制演化过程, 研究裂纹聚结和裂缝填充的破坏行为。

方法

1. 在SPH框架下, 分别采用张拉损伤模型和Drucker-Prager模型计算材料的张拉破坏和剪切破坏; 模拟一系列巴西圆盘试样的破坏行为并与试验结果对比, 验证所提SPH方法是否可用于模拟岩石的破坏机制演化。2. 通过统计分析, 研究不同裂缝倾角和材料属性联合作用对试样宏观破坏形态及力学响应的影响。

结论

1. 对于含未填充裂缝的圆盘试样, 岩桥区裂纹的聚结机制受裂缝倾角和材料性能的组合影响。2. 对于含填充裂缝的圆盘试件, 当圆盘和填充材料的抗拉强度与粘聚力的比值接近时, 试样的张拉损伤的增长速度更快, 使得整个试件表现更多的脆性特征。3. 随着充填物分布不均匀程度的增加, 试样张拉损伤的增长速率降低, 且圆盘试样展现出更多的延性特征; 当预制裂缝倾角接近45°时, 填充物的影响更大。