Experimental investigation of the thermal effects of frost susceptible soils
Newell, Zachary Allen
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Damages to engineering structures attributed to frost action of subgrade soils amounts to millions of dollars annually. Theoretical research has been conducted to examine the details of the frost action phenomenon since the 1940's. However, a reliable and practical approach for evaluating the frost susceptibility of soils is nonetheless a goal that has eluded engineers and scientists alike. The research presented herein focuses on the procedures necessary to obtain a numerical model capable of predicting the thermal response of frost susceptible soils. A field facility was designed and constructed with the purpose of measuring and comparing in-situ frost heave characteristics with laboratory-scale test results. A laboratory-testing device was also designed, constructed, and instrumented in order to measure the thermal response of various soil types in a controlled freezing environment. Geotechnical index testing was conducted on the soil types used in the freezing experiments to fully characterize the soils and examine potential correlations between common soil index properties and frost action behavior. The results of the first season of experimentation provided the framework for a testing protocol necessary for the development of a predictive numerical model. The data obtained from the laboratory tests was used to calculate a new engineering parameter called the segregation potential (SP), which was used as an input into the numerical model developed throughout this research. The model simulated the freezing and thawing characteristics of the soil type found at the field facility. The simulated results were then compared to the in-situ frost action behavior observed at the facility. An improved testing protocol is necessary to obtain more accurate and consistent results. As this research progresses and laboratory testing proceeds, a more extensive database will be acquired and used to build empirical correlations between the thermal and geotechnical index properties of frost susceptible soils. Furthermore, continued research will allow for the advancement of a predictive numerical model that design engineers could use to simulate and predict the freezing and thawing effects of frost susceptible soils incorporated into common engineering structures.