An investigation of single sand particle fracture using X-ray micro-tomography
An investigation of single sand particle fracture using X-ray micro-tomography
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DOI：
10.1680/geot.4.p.157
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发表时间：
2015-09
期刊：
影响因子：
5.8
通讯作者：
B. Zhao;G. Viggiani;M. Jiang
中科院分区：
文献类型：
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作者：
B. Zhao;G. Viggiani;M. Jiang
颗粒破碎对于了解砂土的力学行为具有重要意义，并与许多岩土工程问题有关。为了对单个砂粒在单颗粒压缩下的破碎机理有新的认识，本研究将力学试验与现场进行的三维X射线微计算机断层扫描(μCT)相结合，即在加载过程中。研制了一种新型微型加载装置，用于在实验室纳米聚焦X射线CT内进行原位压缩测试。对8个颗粒、4个LBS颗粒和4个高分解花岗岩(HDG)颗粒进行了试验，研究了它们不同的断裂机理。使用了一系列图像处理和分析技术来获得定性和定量的结果。确定LBS和HDG颗粒断口形态的最重要因素分别是颗粒形态和初始微观结构。观察到了偏离简单垂直劈裂的多种断裂模式，特别是在HDG颗粒中。加载过程中形貌参数的变化与断裂机制和材料性能有关，与初始值无关。LBS和HDG颗粒的碎裂均符合分形分布，表明碎裂具有尺度不变性。发现了不同的耗能机制。摩擦耗散的能量逐渐超过了产生新表面所耗散的能量。
Particle breakage is of fundamental importance for understanding the mechanical behaviour of sands and is relevant to many geotechnical engineering problems. In order to gain new insights into the mechanism of breakage of individual sand particles under single-particle compression, this study combines mechanical tests with three-dimensional X-ray micro-computed tomography (μCT) performed ‘in situ’, that is, during loading. A novel mini-loading apparatus was developed to perform in-situ compression testswithin a laboratory nanofocus X-ray CT. The testswere performed on eight particles, four Leighton Buzzard sand (LBS) particles and four highly decomposed granite (HDG) particles, to study their different fracture mechanisms. A series of image processing and analysing techniques was utilised to obtain both qualitative and quantitative results. The most important factors in determining the fracture patterns of the LBS and HDG particles were found to be particle morphology and initial microstructure, respectively. Versatile fracture patterns deviating from simple vertical splitting were observed, particularly in HDG particles. The change of morphology parameters during loading was found to depend on the fracture mechanisms and material properties, independently of their initial values. The fragments of both the LBS and HDG particles satisfy the fractal distribution, which indicates that the fragmentation is scale invariant. Different energy dissipation mechanisms were found. The energy dissipation by friction gradually prevails against the energy dissipated in generating new surfaces.