On the kinematics of shelly carbonate sand using X-ray micro tomography
On the kinematics of shelly carbonate sand using X-ray micro tomography
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DOI：
10.1016/j.enggeo.2019.105268
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发表时间：
2019-11-01
影响因子：
7.4
通讯作者：
Fonseca, Joana
中科院分区：
文献类型：
--
作者：
Kong, Deqiong;Fonseca, Joana
贝壳碳酸盐砂是高度可压缩的土壤，因为其松散且复杂的结构在负载下容易塌陷。准确评估晶粒尺度上发生的物理现象对于更好地理解和建模这种材料的机械行为至关重要。本文通过分析在里程计压缩过程中获取的原位 4D X 射线断层扫描图像，对贝状碳酸盐砂的颗粒运动学进行了研究。对来自波斯湾的两种沙子进行了研究，分为粗级配和细级配。这里使用自适应分水岭分割技术来在加载之前识别图像中的颗粒，并采用数字体积相关（DVC）技术来获得每个颗粒在加载下的位移场。位移场用于在新位置重建颗粒并计算相关的平移和旋转。进行了广泛的统计分析，以证明晶粒形态和局部结构（协调数）对晶粒运动学的影响。这里提出的新发现揭示了导致贝状碳酸盐砂可压缩结构的颗粒重排机制，并且对于更好地了解其他弱颗粒砂和/或具有开放结构的硅砂也至关重要。
Shelly carbonate sands are highly compressible soils due to the susceptibility of their loose and intricate fabric to collapse under loading. An accurate assessment of the physical phenomena taking place at the grain-scale is critical for a better understanding and modelling the mechanical behaviour of this material. This paper presents a study on the grain kinematics of shelly carbonate sand through analysis of in-situ 4D X-ray tomography images acquired during oedometer compression. Two sands from the Persian Gulf, with coarse and fine grading, were investigated. An adaptive watershed segmentation technique is used here to identify the grains in the image(s) prior to loading and a digital volume correlation (DVC) technique is employed to obtain the displacement field of each grain under loading. The displacement fields are used to reconstruct the grains in their new positions and compute the associated translation and rotation. An extensive statistical analysis was carried out to demonstrate the effect of grain morphology and local fabric (coordination number) on grain kinematics. The new findings presented here shed light on the mechanisms of grain rearrangement leading to the compressible fabric of shelly carbonate sands and, are also critical, to better understand other weak grained sands and/or silica sands with an open fabric.