3D Assessment of Particle Morphology and its Influence on Friction, Dilatancy, and Fabric Evolution of Sheared Granular Materials

非胶结颗粒材料的强度特性和变形特性在很大程度上取决于颗粒结构的组构或几何形状以及颗粒间的摩擦。颗粒形态（表面粗糙度、圆度和球形度）和微观性质在影响颗粒材料的工程行为中起着重要作用。2D中颗粒材料的形态、结构和颗粒相互作用的定量描述是很好理解的，并且自20世纪70年代初以来一直是广泛研究的主题;然而，3D中的类似测量仍然非常有限。文献缺乏一个系统的三维研究，实验研究颗粒的球形度，形状和表面粗糙度对摩擦，粘性和织物演变的剪切颗粒材料的影响。在这项研究中，颗粒形状和球形度的精确定量测量将获得高分辨率的三维同步辐射计算机断层扫描（SCT）图像和天然硅砂颗粒的表面粗糙度补充原位三维SCT成像的颗粒相互作用在三轴试样。这些测量将被用来评估颗粒形态对织物，摩擦，粘性性能，临界状态和应变局部化的颗粒材料的影响。这项研究将提供关键的实验测量，以校准和验证模型，从而更好地了解颗粒材料的行为。 此外，它将回答有关影响颗粒材料强度特性的内在颗粒特性的关键基本问题。这种理解的增加将促进新理论的发展，以预测粒状材料的工程行为。这项研究，除了丰富土木和环境工程计划，（一）将提供急需的实验测量，以校准模型，处理沙的行为;（二）将影响研究界和促进技术转让;（三）将涉及少数民族/女本科生进行尖端工程研究;（iv）为土木工程本科生提供丰富的研究经验;（v）通过让高中生参与我们的研究，将有助于吸引下一代科学家，激发他们对土木工程领域的兴趣，并帮助提高下一代土木工程教育工作者和专业人员的素质;以及（vi）将为初中和高中学生量身定制新的尖端教育材料。

Strength properties and deformation characteristics of uncemented granular materials are to a large extent derived from the fabric or geometry of the grain structure and inter-particle friction. Particle morphology (surface roughness, roundness, and sphericity) and micro-properties play a significant role in influencing the engineering behavior of granular materials. Quantitative description of morphology, fabric, and particle interaction of granular materials in 2D is well understood and has been a subject of extensive research since the early 1970s; however, similar measurements in 3D are still very limited. The literature lacks a systematic 3D study that experimentally investigates the effects of particles sphericity, shape, and surface roughness on friction, dilatancy, and fabric evolution of sheared granular materials. In this research, accurate quantitative measurements of particle shape and sphericity will be obtained from high-resolution 3D synchrotron computed tomography (SCT) images and surface roughness of natural silica sand particles complemented by in situ 3D SCT imaging of particle interaction within triaxial specimens. These measurements will be used to assess the influence of particle morphology on fabric, friction, dilatancy properties, critical state, and strain localization of granular materials. This research will provide critical experimental measurements to calibrate and validate models allowing a better understanding of the behavior of granular materials. Also, it will answer key fundamental questions about intrinsic particle properties that affect strength properties of granular materials. This increased understanding will spur the development of new theories dealing with predicting the engineering behavior of granular materials. The research, besides enriching the Civil and Environmental Engineering program, (i) will provide much needed experimental measurements to calibrate models that deal with the behavior of sand; (ii) will impact the research community and promote technology transfer; (iii) will involve minority/female undergraduate students in conducting cutting edge engineering research; (iv) will provide an enriching research experience for undergraduate civil engineering students; (v) will help engage the next generation of scientists by involving high school students in our research, to spark their interest in the field of civil engineering and help contribute to the quality of the next generation of civil engineering educators and professionals; and (vi) will produce new, cutting-edge educational materials tailored for middle and high school students.