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Evolution of texture and internal stresses within polycrystalline rock salt using in situ 3D synchrotron computed tomography and 3D X-ray diffraction
Journal of Applied Crystallography ( IF 6.1 ) Pub Date : 2021-09-13 , DOI: 10.1107/s1600576721007809
Amirsalar Moslehy , Khalid A. Alshibli , Timothy J. Truster , Peter Kenesei , Wadi H. Imseeh , Zaher Jarrar , Hemant Sharma

Rock salt caverns have been extensively used as reliable repositories for hazardous waste such as nuclear waste, oil or compressed gases. Undisturbed rock salt deposits in nature are usually impermeable and have very low porosity. However, rock salt formations under excavation stresses can develop crack networks, which increase their porosities; and in the case of a connected crack network within the media, rock salt may become permeable. Although the relationship between the permeability of rock salt and the applied stresses has been reported in the literature, a microscopic study that investigates the properties influencing this relationship, such as the evolution of texture and internal stresses, has yet to be conducted. This study employs in situ 3D synchrotron micro-computed tomography and 3D X-ray diffraction (3DXRD) on two small-scale polycrystalline rock salt specimens to investigate the evolution of the texture and internal stresses within the specimens. The 3DXRD technique measures the 3D crystal structure and lattice strains within rock salt grains. The specimens were prepared under 1D compression conditions and have shown an initial {111} preferred texture, a dominant {110}⟨110⟩ slip system and no fully connected crack network. The {111} preferred texture under the unconfined compression experiment became stronger, while the {111}⟨110⟩ slip system became more prominent. The specimens did not have a fully connected crack network until applied axial stresses reached about 30 MPa, at a point where the impermeability of the material becomes compromised due to the development of multiple major cracks.

中文翻译:

使用原位 3D 同步加速器计算机断层扫描和 3D X 射线衍射研究多晶岩盐内部结构和内应力的演变

岩盐洞穴已被广泛用作危险废物(如核废物、石油或压缩气体)的可靠储存库。自然界中未受干扰的岩盐矿床通常是不透水的,孔隙率非常低。然而,在开挖应力作用下,岩盐地层会形成裂缝网络,从而增加其孔隙度;在介质中存在连接的裂缝网络的情况下,岩盐可能会变得可渗透。尽管岩盐渗透率与施加应力之间的关系已在文献中有所报道,但尚未进行微观研究来研究影响这种关系的特性,例如质地和内应力的演变。本研究采用原位对两个小型多晶岩盐样品进行 3D 同步加速器显微计算机断层扫描和 3D X 射线衍射 (3DXRD),以研究样品内部结构和内应力的演变。3DXRD 技术测量岩盐颗粒内的 3D 晶体结构和晶格应变。试样是在一维压缩条件下制备的,并显示出初始 {111} 优先纹理,主要的 {110}⟨1 1 0⟩ 滑移系统和没有完全连接的裂纹网络。无侧限压缩实验下的{111}优选纹理变得更强,而{111}⟨1 10⟩滑动系统变得更加突出。直到施加的轴向应力达到约 30 MPa 时,试样才具有完全连接的裂纹网络,此时材料的抗渗性因多个主要裂纹的发展而受到损害。
更新日期:2021-10-06
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