基于AE和DIC的多裂隙岩石力学特性及破坏演化研究

    Study on the mechanical properties and failure evolution of multi-fractured rock based on AE and DIC techniques

    • 摘要: 为研究多裂隙岩石力学特性及破坏演化规律,本文采用石膏类岩石材料制备了具有不同裂隙角度及裂隙数量的试件,开展了单轴压缩试验,并结合声发射(AE)与数字散斑(DIC)技术研究了裂隙数量(3条与9条)和角度(0°、30°、45°、60°、90°)对类岩石试件力学特性及破坏演化规律的影响。研究结果表明,裂隙数量与角度显著影响试件强度和破坏模式。抗压强度随裂隙角度增大呈“V”形变化,30°时强度最低,90°时强度最高但数量增加导致的强度劣化最显著(降幅达23%)。AE监测揭示能量释放具有角度依赖性:0°和90°时裂隙扩展缓慢,能量释放分散;而30°至60°时裂隙扩展剧烈,45°时声发射振铃计数峰值最高,能量释放集中。多裂隙交互作用使高角度裂隙的能量释放机制更复杂。DIC全场应变分析表明,应变集中始于裂隙尖端,多裂隙试件应变场更复杂,最大主应变值显著增高(从3条裂隙的2.1%增至9条裂隙的4.6%),表明裂隙密度增加加剧了材料整体性劣化和协同破坏。破坏模式受倾角控制:小角度以张拉破坏为主,中等角度转为张拉-剪切复合破坏,高角度时回归张拉主导。该研究深入揭示了多裂隙岩体的力学行为与破坏机制,为煤矿地下水库等工程的稳定性评估与支护设计提供了重要理论依据。

       

      Abstract: To investigate the mechanical properties and failure evolution of multi-fractured rocks, gypsum-based rock-like materials are employed to fabricate specimens with different fracture numbers and fracture inclinations. Uniaxial compression tests are carried out in conjunction with acoustic emission(AE) monitoring and digital image correlation(DIC) techniques to systematically analyze the effects of fracture number(3 and 9) and fracture angle(0°, 30°, 45°, 60°, 90°) on the mechanical behavior and failure evolution of the specimens. Experimental observations show that both fracture number and fracture inclination have a pronounced influence on the compressive strength and failure modes. The uniaxial compressive strength of the specimens varies with fracture angle in a clear V-shaped pattern: the minimum strength occurs at a fracture angle of 30°, whereas the maximum strength is observed at 90°. However, specimens with fractures oriented at 90° exhibit the strongest sensitivity to fracture number, and increasing the fracture number from 3 to 9 results in the most significant strength degradation at this angle, with a maximum reduction of 23%. AE monitoring reveals distinct angle-dependent energy release behaviors during the loading process. For specimens with fracture angles of 0° and 90°, fracture propagation is relatively slow and the released energy is distributed over a longer period. In contrast, specimens with fracture angles between 30° and 60° experience rapid crack propagation accompanied by concentrated energy release. The highest AE ring-down count peak is recorded at a fracture angle of 45°, indicating the most intense fracture activity. Moreover, interactions among multiple fractures further increase the complexity of the energy release mechanisms, particularly in specimens with high fracture angles. Full-field strain analysis based on DIC indicates that strain localization consistently initiates at fracture tips and subsequently evolves along paths controlled by fracture geometry. Compared with specimens containing fewer fractures, specimens with higher fracture numbers exhibit more complex strain field distributions and significantly larger maximum principal strain values, increasing from approximately 2.1% for specimens with 3 fractures to 4.6% for those with 9 fractures. This behavior suggests that increasing fracture density accelerates material integrity degradation and promotes synergistic failure. The failure mode is predominantly governed by fracture inclination. Tensile-dominated failure is observed at low fracture angles, which gradually transitions to tensile-shear composite failure at intermediate angles, and finally returns to tensile-dominated failure at high angles. These results provide deeper insight into the mechanical behavior and failure mechanisms of multi-fractured rock masses and offer important theoretical support for stability evaluation and support design in engineering applications such as coal mine underground reservoirs.

       

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