Modified Thermomechanical Triaxial Cell for Microscopic Assessment of Clay Fabric Using Synchrotron X-Ray Diffraction
Modified Thermomechanical Triaxial Cell for Microscopic Assessment of Clay Fabric Using Synchrotron X-Ray Diffraction
复制标题
使用同步加速器 X 射线衍射对粘土织物进行微观评估的改进热机械三轴单元
DOI：
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发表时间：
2020
影响因子：
1.6
通讯作者：
S. M. Zeinali
中科院分区：
文献类型：
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作者：
Sherif L. Abdelaziz;Karam A. Jaradat;S. M. Zeinali
本文提出了一种热机械三轴细胞修改，以适应内同步加速器X射线衍射（XRD）光束线，旨在评估热诱导的微观结构变化饱和粘土原位条件下。了解这些热诱导的微观结构的变化粘土将解释一些了解不多或误解的概念，这些土壤的热力学行为，这反过来，将允许更强大的地热和能源应用的地质结构设计。与其他技术相比，同步加速器衍射提供（1）与台式XRD相比对小变化的高准确度和灵敏度，以及（2）在原位条件下评估微结构变化的能力（即，应力、饱和度和温度）。本文首先介绍了改进型三轴盒的设计和各种材料的选择。基于这种设计，建议使用（1）5至7 mm范围内的样品直径，以最大限度地减少修剪期间的样品干扰和X射线扫描期间的X射线背景散射，以及（2）具有丙烯酸壁的透明池，氮气作为限制流体和氯丁橡胶膜，因为所有考虑的池壁材料（即，丙烯酸和铝），限制气体（即，氮气、二氧化碳、氩气和压缩空气），和膜材料（即，乳胶和氯丁橡胶）导致精确衍射测量。修改后的细胞，然后被用来评估的颗粒重取向的变化后的饱和和固结阶段，以及加热负荷的正常固结高岭石粘土。结果表明，饱和和固结阶段的颗粒重新定向垂直于样品的纵轴，这是相同的方向，孔隙水流入和流出的样品。由于加热，观察到进一步的颗粒重新取向。
This article presents a thermomechanical triaxial cell modified to fit inside a synchrotron X-ray diffraction (XRD) beamline aiming to assess thermally induced microstructural changes in saturated clays under in situ conditions. Understanding these thermally induced microstructural alternations in clays will explain some of the poorly understood or misunderstood concepts about the thermomechanical behavior of these soils; this, in turn, will allow more robust designs of geostructures for thermal and energy applications. Compared to other techniques, synchrotron diffraction provides (1) high accuracy and sensitivity to small changes compared to benchtop XRD and (2) the ability to assess microstructure changes under in situ conditions (i.e., stress, saturation, and temperature). The design and selection of the various materials used in the modified triaxial cell are first presented. Based on this design, it is recommended to use (1) sample diameters in the 5 to 7–mm range to minimize sample disturbance during trimming and X-ray background scattering during X-ray scans and (2) a transparent cell with acrylic walls, with nitrogen gas as the confining fluid and neoprene membranes, since all considered cell wall materials (i.e., acrylic and aluminum), confining gases (i.e., nitrogen, carbon dioxide, argon, and compressed air), and membrane materials (i.e., latex and neoprene) result in accurate diffraction measurements. The modified cell was then used to assess the changes in particle reorientations of a normally consolidated kaolinite clay after the saturation and consolidation stages as well as the heating load. The results showed that the saturation and consolidation stages reoriented the particles perpendicular to the longitudinal axis of the sample, which is the same direction as the pore water flowing in and out of the sample. Further particle reorientations were observed due to heating.