Development of a Modified Cam-Clay Model for Unsaturated Soils under Elevated Temperatures

Understanding the temperature dependency of the mechanical behavior of unsaturated soils is crucial for modeling their performance in environments subject to significant thermal variations. This study addresses the need for advanced constitutive models to support emerging applications in geotechnical and geoenvironmental engineering. A modified Cam-Clay model was developed to incorporate nonisothermal formulations for soil-suction stress, effective stress, and the water retention curve, enabling the prediction of thermo-elastoplastic behavior in unsaturated soils. The formulation accounts for temperature effects on key parameters, including enthalpy, contact angle, and surface tension. A series of closed-form equations is introduced to describe temperature-dependent suction and yield mechanisms within a critical state framework. The model is calibrated and validated using experimental datasets, including suction-controlled triaxial tests and volumetric strain measurements at elevated temperatures. Results show strong agreement with observed data and improved accuracy compared to existing models. The proposed framework offers a robust and predictive tool for analyzing temperature-sensitive behavior in unsaturated soils, with applications in nuclear waste containment, energy geostructures, and climate-resilient infrastructure.