Date of Award

Spring 2025

Project Type

Thesis

Program or Major

Civil and Environmental Engineering

Degree Name

Master of Science

First Advisor

Jo E. Sias

Second Advisor

Eshan V. Dave

Third Advisor

Mohamed Elshaer

Abstract

The increasing threat of climate change and sea level rise makes it important to have a more adaptive pavement design approach. The AASHTO 1993 pavement design method, used by 55% of U.S. state transportation agencies, assumes a constant subgrade modulus value. This simplification does not take into account the changing subgrade conditions that are affected by environmental factors like rising or fluctuating groundwater levels. This thesis presents a method to include changes in subgrade modulus due to groundwater level variations in the AASHTO 1993 framework, making the pavement design more accurate and reliable under changing conditions.The study begins with a moisture sensitivity analysis to assess the impact of varying moisture contents on the subgrade modulus under different soil classifications, layer thicknesses, and constant moisture conditions. This analysis helps establish a foundational understanding of how changes in moisture content influence pavement performance. Building on this, the research utilizes multi-layer elastic theory to derive predictive models capable of adjusting subgrade modulus values relative to groundwater table fluctuations. This modeling approach incorporates both depth and time variables to calculate an equivalent modulus that dynamically responds to changing groundwater levels throughout the pavement’s lifespan, predicting how the structure will degrade over time under variable moisture regimes. This aspect of the methodology is critical for developing a deterioration curve that reflects the expected performance of the pavement, considering future environmental conditions. The application of this methodology allows for an adaptive pavement design process that can accommodate environmental changes. By improving the accuracy and reliability of pavement design under variable conditions, this research contributes to the field of pavement engineering, ensuring safer and more reliable infrastructure in the face of uncertain climatic futures.

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