Abstract In underground excavations, different failure features can be induced by complex geological stresses. Therefore, many researchers have investigated rock behaviour and failure mechanisms under high-stress conditions. This study investigated the different failure characteristics to determine the stress-induced cracking mechanisms. Accordingly, a series of tests were performed on a volcanic rock (rhyodacite) under one- to three-dimensional stress states. The results indicated that the samples exhibited different failure characteristics/modes under different stress states. Under 1-D and 2-D compression, the rock exhibited unstable brittle failure induced by tensile cracking (Mode I fracture). Under axisymmetric triaxial stress (σ1 > σ2 = σ3 > 0), the rock exhibited stable failure, and as σ3 increased, the failure mode transitioned from Mode I fracture to Mode II fracture to distributed cataclastic failure. In contrast, under a three-dimensional differential stress state (σ1 > σ2 > σ3 > 0), the risk of unstable failure increased with increasing σ2, and the rock exhibited localized shear failure (Mode II fracture). Based on the acoustic emission (AE)-based cracking classification method, further studies were also conducted on the failure mechanism. Finally, based on the energy release and cracking propagation, the mechanism of the σ2 effect on unstable failure was assessed.

中文翻译：

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火山岩应力致裂机理的试验研究

摘要 在地下开挖中，复杂的地质应力可诱发不同的破坏特征。因此，许多研究人员对高应力条件下的岩石行为和破坏机制进行了研究。本研究调查了不同的失效特征，以确定应力引起的开裂机制。因此，在一维到三维应力状态下对火山岩（流纹长石）进行了一系列测试。结果表明，样品在不同应力状态下表现出不同的失效特征/模式。在 1-D 和 2-D 压缩下，岩石表现出由拉伸开裂（I 型断裂）引起的不稳定脆性破坏。在轴对称三轴应力（σ1 > σ2 = σ3 > 0）下，岩石表现出稳定破坏，随着σ3的增加，破坏模式由I型断裂转变为II型断裂，再到分布式爆裂破坏。相比之下，在三维微分应力状态下（σ1 > σ2 > σ3 > 0），不稳定破坏的风险随着σ2的增加而增加，岩石表现出局部剪切破坏（II型断裂）。在基于声发射（AE）的裂纹分类方法的基础上，还对破坏机制进行了进一步研究。最后，基于能量释放和裂纹扩展，评估了σ2效应对不稳定破坏的机制。并且岩石表现出局部剪切破坏（模式 II 断裂）。在基于声发射（AE）的裂纹分类方法的基础上，还对破坏机制进行了进一步的研究。最后，基于能量释放和裂纹扩展，评估了σ2效应对不稳定破坏的机制。并且岩石表现出局部剪切破坏（模式 II 断裂）。在基于声发射（AE）的裂纹分类方法的基础上，还对破坏机制进行了进一步的研究。最后，基于能量释放和裂纹扩展，评估了σ2效应对不稳定破坏的机制。