Graduate Defense: James Mazzagotte

Thesis Information

Title: Developing Relationships Between Macroporosity And Tensile Strength By Imaging Failure Planes

Program: Master of Science in Civil Engineering

Advisor: Dr. Nick Hudyma, Civil Engineering

Committee Members: Dr. Bhaskar Chittoori, Civil Engineering; Dr. Mojtaba Sadegh, Civil Engineering; and Dr. Alan Harris, Electrical & Computer Engineering

Abstract

Porosity, the measure of void spaces within rock structures, plays a pivotal role in determining properties such as density, hydraulic conductivity, and mechanical strength, encompassing both microporosity and macroporosity. While numerous studies have investigated the influence of porosity on compressive strength and stiffness across various rock types, less attention has been given to its impact on tensile strength, especially in extrusive igneous formations like vesicular basalt. This study addresses this gap by quantifying the correlation between macroporosity and tensile strength in vesicular basalt. The investigation utilized non-destructive methods, including machine learning and manual image analysis, to conduct porosity calculations, which were divided into two sections: specimen porosity and failure plane porosity. Specimen porosity was determined through the specific gravity method with a constant of 3.0 and the application of a modified Segment Anything Model (SAM) for image segmentation. Meanwhile, failure plane porosity was assessed using SAM on stitched and focused stacked images, alongside manual calculations employing IC Measure software. Results indicated a poor correlation between porosity values obtained via specific gravity and SAM due to segmentation challenges inherent in SAM. SAM tended to yield higher porosity values, thereby affecting its correlation with tensile strength. Additionally, surface porosity was deemed inadequate for estimating overall specimen porosity due to the heterogeneous nature of macropores. Discrepancies in failure plane porosity analysis were attributed to SAM’s tendency to misidentify macropores, necessitating manual corrections. However, despite these challenges, the use of failure plane porosity significantly improved the correlation with tensile strength compared to specimen porosity assessment. Overall, while the assessment of failure plane porosity presented obstacles, it showed promise in enhancing the understanding of the relationship between porosity and tensile strength.