Heterogeneous rock contains numerous pre-existing three-dimensional (3D) cracks, which control its mechanical and fracturing properties. Considerable effort has been devoted to studying the volumetric fracturing behaviour of rock under static loading conditions. Although rock masses are often subject to dynamic impacts such as earthquakes and blasting, the mechanical and volumetric fracturing behaviour of rock under dynamic loading is still poorly understood. In this paper, dynamic laboratory tests were performed on 3D-printed artificial rock samples with 3D embedded flaws created during three-dimensional printing (3DP), with the aim of studying the volumetric fracturing and mechanical properties of these samples under impact with high strain rate. The results show that the dynamic compressive strength and the tangent modulus decrease with an increasing number of flaws, but have very limited effects on the ratio of the fracture initiation stress of the first crack to the peak stress of the sample, the maximum axial strain of the sample and the volumetric fracturing behaviour of the sample. The tensile failure of a sample is caused by the continuous extension of wing cracks from the outer flaw tips. The mechanical and volumetric fracturing behaviour of samples with 3D embedded flaws are strain rate dependent. The tangential modulus and the ratio of the fracture initiation stress of the crack to the peak stress increase significantly when the loading type changes from static compression to dynamic compression. Under dynamic compression, wing cracks can continuously extend to the sample ends, whereas under static compression, wing cracks can intermittently extend only a limited distance. Moreover, the fracturing behaviour of 3D flaw differs from that of 2D flaws under dynamic loading. Under high strain rate loading, wing cracks generated at 3D flaw tips lead to splitting failure of the sample, while shear cracks formed at 2D flaw tips result predominant shear failure of the sample. The findings in this paper could facilitate a better understanding of rock failure subjected to dynamic loading conditions.

中文翻译：

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动态载荷下三维打印类岩石样品的力学和体积破裂行为

非均质岩石包含许多预先存在的三维 (3D) 裂缝，这些裂缝控制着其机械和压裂特性。大量的努力致力于研究岩石在静态载荷条件下的体积压裂行为。尽管岩体经常受到地震和爆破等动态冲击，但对岩石在动态载荷下的力学和体积破裂行为仍知之甚少。在本文中，对 3D 打印的人造岩石样品进行了动态实验室测试，该样品在 3D 打印 (3DP) 过程中产生了 3D 嵌入缺陷，目的是研究这些样品在高应变率冲击下的体积破裂和力学性能。 . 结果表明，动态抗压强度和切线模量随着缺陷数量的增加而降低，但对试样的第一裂纹断裂起始应力与峰值应力之比的影响非常有限，最大轴向应变为样品和样品的体积破裂行为。样品的拉伸破坏是由外裂纹尖端的翼裂纹不断延伸引起的。具有 3D 嵌入缺陷的样品的机械和体积破裂行为取决于应变率。当加载类型从静态压缩变为动态压缩时，切向模量和裂纹的断裂起始应力与峰值应力的比值显着增加。在动态压缩下，翼裂纹可以不断延伸到样品端部，而在静态压缩下，机翼裂纹只能间歇性地延伸有限的距离。此外，动态载荷下 3D 缺陷的断裂行为与 2D 缺陷的断裂行为不同。在高应变率载荷下，3D裂纹尖端产生的翼状裂纹导致样品的分裂破坏，而2D裂纹尖端形成的剪切裂纹导致样品的主要剪切破坏。本文的研究结果有助于更好地理解动态载荷条件下的岩石破坏。而在二维缺陷尖端形成的剪切裂纹导致样品的主要剪切破坏。本文的研究结果有助于更好地了解动态载荷条件下的岩石破坏。而在二维缺陷尖端形成的剪切裂纹导致样品的主要剪切破坏。本文的研究结果有助于更好地了解动态载荷条件下的岩石破坏。