PARTICLE MORPHOLOGY AND ITS INFLUENCE ON FRICTION AND DILATANCY OF SANDS

Particle morphology outlines the general analytical method used to describe soil particles’ structure and shape. The characteristics defining this term include sphericity, roundness, and surface texture. Particle morphology has a significant influence on sand behavior and consequently affects dilatancy and friction. Understanding the relationship between shear strength parameters and particle morphology answers fundamental questions about the mechanics of granular materials in general and has the potential to enhance the development of advanced constitutive models that describe granular materials’ behavior.

Many researchers have reported measurements for sphericity, roundness, and surface texture using both two-dimensional (2D) and three-dimensional (3D) images to analyze the effects on granular materials’ friction and dilatancy angles. This thesis investigates the influence of morphology measurements from 3D images on friction and dilatancy of three types of sands (#1 Dry Glass, GS#40 Columbia, and F-35 Ottawa Sand) and on glass beads. A series of direct shear experiments were conducted at various normal stresses and densities to achieve this goal.

Experimental measurements of friction and dilatancy angles were compared to findings in a previous study. A stepwise regression analysis was performed to develop statistical models predicting friction and dilatancy using the specimen’s relative density, normal stress, and particle morphology as input parameters. This thesis discusses how these explanatory variables affect the model and compares the experimental results with the predicted values. A reasonable agreement is found between the model’s predictions and the experimental results.

The development of simple statistical models capable of accurately predicting friction and dilatancy values has a major impact on many field applications (e.g., processing granular materials for industrial and engineering purposes, foundation design, landslides, agricultural and pharmaceutical products, and future research on granular materials’ behavior). This study contributes to further advancements in theories predicting granular materials’ behavior and provides experimental evidence to support improvements of constitutive models that describe the behavior of sands.