Frost action below road pavements and structures supported on shallow foundations results in significant long-term maintenance problems in most temperate zones in which seasonal soil freezing occurs. The problem is widespread, and is becoming increasingly important as wheel loadings, traffic frequency, and costs of pavement structures increase. Over the past thirty years, phenomenological studies have been conducted pertaining to development of viscoelastoplasticity models of frozen soils. However, a practical approach is needed for evaluating the frost susceptibility of soils and for predicting the magnitude of strength reduction, heave, and settlement of soils exposed to repeated freeze-thaw cycles.This project addresses the problem of quantifying effects of frost action including heave that occurs during the freezing process, and settlement that occurs during thaw. Geotechnical and engineering mechanics principles will be used to develop practical methods for investigating and analyzing the long-term behavior of soils subjected to repeated cycles of freezing and thawing, with an emphasis on frost heave aspects related to construction and performance of pavement structures. Compressibility and settlement characteristics of thawing soils will also be addressed, with an emphasis in developing practical methods and correlations using in situ devices and laboratory tests.Experimental and analytical research is proposed to develop systematic and practical methods that can be applied to the analysis and design of highway pavement sections and shallow foundations constructed in cold climates. The research will focus on regional soil conditions and seasonal variations that are common to the state of Montana and the inter-mountain region of the United States. The project will make extensive use of geotechnical and snow mechanics equipment currently available in the Civil Engineering Department at Montana State University (MSU).