多重应力作用下深部岩石变形机制的实验探究
Empirical Exploration of Deformation Mechanisms in Deep Rock Exposed to Multiple Stresses
AI总结：
本研究利用新型真三轴仪器开展实验，探究多重应力下深部岩石的变形与断裂机制，明确了主应力对强度、应变、模量等参数的影响规律，指出库仑准则在复杂断裂岩石中的应用局限。
摘要：
为避免测试过程中天然固有缺陷对实验结果的影响，一款最新设计的真三轴仪器已能够复现三个主应力大小各不相同的条件。该实验装置便于研究真三轴应力状态下与4系岩类似的材料的断裂行为。实验结果表明，在真三轴应力条件下，岩石的最大强度受最小主应力和中间主应力的显著影响。具体而言，对于固定的最小主应力（σ3），随着中间主应力（σ2）增大，峰值应变逐渐减小；此外，随着最小主应力（σ3）升高，峰值应变的数值也会降低。试样的杨氏模量随围压升高呈指数增长，随中间主应力增大呈线性增长规律。此外，研究观察到，随着中间主应力升高，黏聚力上升，而内摩擦角下降。真三轴应力条件下试样的破坏模式可分为三类，所有破坏模式的断裂面与σ3之间均存在特定夹角，范围在50至62度之间。此外，通过对比断裂角的计算范围与实际测量范围，发现库仑准则中断裂角（θ）与内摩擦角（ϕ）的关系存在若干局限性，尤其是在含有复杂断裂系统的岩石中。
英文摘要：
To avoid the impact of inherent natural imperfections on experimental outcomes during testing, a recently designed genuine triaxial apparatus has enabled the replication of conditions where the three principal stresses exhibit varying magnitudes. This setup facilitates the examination of fracture behaviors in materials similar to the 4-series under genuine triaxial stress states. The experimental findings revealed that the maximum strength experiences significant influence from the minimum principal stress and the intermediate principal stress in genuine triaxial stress conditions. Specifically, for a fixed minimum principal stress (σ3), there is a progressive reduction in peak strain as the intermediate principal stress (σ2) increases. Moreover, as the minimum principal stress (σ3) rises, the magnitude of peak strain diminishes. The Young's modulus of the specimens exhibits an exponential increase with the augmentation of confining pressure, and it demonstrates a linear growth pattern as the intermediate principal stress increases. Additionally, the cohesion force is observed to rise while the internal friction angle decreases with the elevation of the intermediate principal stress. The failure modes of the specimens in genuine triaxial stress conditions can be categorized into three types, all of which exhibit a specific angle between the fracture surface and σ3, ranging from 50 to 62 degrees. Furthermore, a comparison between the computed range and the actual measurement range of the fracture angle highlights several limitations in the relationship between the fracture angle (θ) and the internal friction angle (ϕ) within the Coulomb criterion, particularly in rocks containing complex fracture systems.
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