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

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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.