Rock fragmentation is a critical process for mineral extraction and for mitigating overstressed rock in geotechnical applications. In this study, 3D-printed concrete was used to simulate the stratified rock mass, and experimental and numerical methods were employed to investigate crack propagation under static expansive loadings in transversely isotropic rocks. Two types of cracks were observed in the experiments: P-type (a crack propagates primarily along the weak layer) and T-type (a crack propagates across the weak layers) cracks. The findings revealed that the orientation of layers significantly influenced the initiation and propagation of cracks, with P-type cracks commonly observed in simpler P-P mode fragmentations and more complex P-P-T modes emerging under higher expansive loadings. P-T-T modes were characterized by the simultaneous presence of the T-type crack after an initial P-type crack. The AE energy levels in the P-P-T and P-T-T modes were much higher than those in the P-P mode. 2D-DDA models were further built to understand the effects of the loading scales, layer angles, and locations of weak layers on the cracking sequences. The results provided detailed insights into stress evolutions and the impact of expansive loadings on crack initiation and propagation.

中文翻译：

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静态膨胀载荷下模拟横向各向同性岩石的岩石碎裂


岩石碎裂是矿物开采和减轻岩土工程应用中岩石过度应力的关键过程。在本研究中，使用 3D 打印混凝土模拟分层岩体，并采用实验和数值方法研究横向各向同性岩石在静态膨胀载荷下的裂纹扩展。在实验中观察到两种类型的裂纹：P 型（裂纹主要沿薄层扩展）和 T 型（裂纹穿过薄层扩展）裂纹。研究结果表明，层的取向显著影响了裂纹的萌生和扩展，P 型裂纹常见于较简单的 P-P 型碎裂，而更复杂的 P-P-T 模式则出现在较高的膨胀载荷下。P-T-T 模式的特征是在初始 P 型裂纹后同时存在 T 型裂纹。P-P-T 和 P-T-T 模式下的 AE 能级远高于 P-P 模式下的声发射能级。进一步构建了 2D-DDA 模型，以了解加载尺度、层角度和薄弱层位置对开裂序列的影响。结果提供了对应力演变以及膨胀载荷对裂纹萌生和扩展影响的详细见解。