Project Overview
The major research goal of this project (NSF CMMI 1054190) is to understand the fundamental issues involved in using heat to improve the properties of unsaturated soils. Four research thrusts are being followed by the students working on this project: (1) understand the variables affecting thermally-induced flow of water in unsaturated soils, including the zone of influence and the time required for this process; (2) understand the impact of temperature on the shear strength and volume of unsaturated soils under low suction magnitudes (nearly saturated conditions); (3) understand the impact of temperature on the shear strength and volume of unsaturated soils under high suction magnitudes (nearly dry conditions); and (4) understand the impact of temperatures on the deformation response of geosynthetic reinforcements used in thermally active  geotechnical systems. In all four thrusts, experimental approaches are being used to understand the fundamental behavior of compacted, unsaturated silt. The results are being used to extend and validate constitutive models originally developed for water-saturated soils. The research thrusts on high and low suctions are being pursued separately due to the different mechanisms of volume change in these conditions, and because of the difference in experimental methodologies to control suction in dry conditions (vapor flow technique) and nearly saturated conditions (axis-translation technique). The findings from these research thrusts are being integrated to evaluate the feasibility of using near-surface geotechnical systems (retaining walls, embankments) as heat sinks for industry or buildings, while at the same time taking advantage of the spurious heat to improve the long-term mechanical response of the geotechnical system. The major educational goal is to develop a communication training program for geotechnical engineers that permits them to communicate their research findings to audiences with different levels of technical background. The outcome of the educational goal is to disseminate research findings to a wide audience and to provide new geotechnical engineers with the skills necessary to communicate the need for innovative solutions in practice.