A mechanistic framework for evaluating the performance of asphalt pavements subjected to frost heave and thaw settlement

QC 20251218

Abstract

Asphalt pavements are subjected to various forms of deterioration throughout their service life due to the combined effects of traffic loading and environmental conditions. In cold regions, the coexistence of subfreezing temperatures and a high moisture content promotes the formation of ice lenses in frost-susceptible soils that may be present in the subgrade layer. This phenomenon, known as frost heave, induces differential upward movement of the ground surface, leading to cracking and surface irregularities in pavements. During the subsequent thawing period, the melting of ice lenses leads to a significant reduction in the stiffness and stability of the underlying soil, thereby compromising the structural integrity of the pavement. This cycle of frost heave and thaw settlement contributes to progressive surface degradation, a phenomenon commonly observed in countries like Sweden, where long winters and moisture-saturated soils are prevalent.

The present thesis proposes a mechanistic framework to assess the performance of asphalt pavements under frost heave and thaw settlement. To achieve this, a thermomechanical frost heave–thaw settlement model is coupled with a thermodynamics-based asphalt damage model. In the frost heave–thaw settlement component, thermal and mechanical fields are coupled through a porosity evolution function, which implicitly accounts for water seepage during frost heave. Notably, the proposed model introduces a new approach in which the formation of ice lenses during frost heave and the excess water introduced into soil composite during the thawing phase are treated analogously to the healing and damage processes in continuum damage mechanics. 

The mechanical behavior of asphalt materials is modeled using a continuum constitutive framework capturing viscoelasticity, viscoplasticity, and material degradation. The formulation is developed in the context of finite strain theory and is grounded in thermodynamic principles governing irreversible processes. In this model, damage initiation and evolution are ascribed to the restored viscoelastic energy. 

The proposed framework is implemented and evaluated across study scenarios that include both uniform and non-uniform frost heave and thaw settlement. The scenarios comprise isolated freeze-thaw cycles and full-scale cases using measured climate data from the city of Kiruna in northern Sweden. The results show that the framework effectively captures the frost action within the soil by modeling the evolution of porosity, the distribution of ice and liquid water contents, and the associated ground surface deformations. In addition, it enables the analysis of the subsequent propagation of damage within the asphalt layer. The framework also serves as a valuable tool for assessing the effectiveness of various mitigation strategies aimed at alleviating the detrimental effects of annual ground surface deformations induced by frost heave and thaw settlement.

urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-374330