Temperature Effects on Soil Behavior in Relation to Ground-Sourced Bridge Deck Deicing Systems

The effect of temperature on soil behavior is gaining importance as energy foundations are utilized for heating and cooling of buildings as well as for deicing of bridge decks in the winter. Energy foundations can be as pathways to utilize the ground as a heat source. However, the induced temperature change can affect soil behavior and influence the soil-pile interaction. This paper describes the effect of temperature changes on soil behavior. The results of temperature controlled triaxial tests and oedometer tests from previous studies are evaluated to determine the general trends of soil behavior in response to temperature increase. A comprehensive review of the literature shows that an increase in temperature induces changes in the pore water pressure, volume, shear strength, and preconsolidation pressure of the soil. During an undrained triaxial test, an increase in temperature of 35⁰C can result in excess pore water pressures up to 80% of the initial consolidation pressure. The change in volume during a drained triaxial shear test not only depends on the temperature history but also on the overconsolidation ratio (OCR). Normally consolidated clays exhibit a highly contractive behavior response to increased temperatures. On the other hand, clays having high OCR can show dilative behavior during thermal loads. As overconsolidation ratio increases, clays tend to be more dilative when thermally loaded. The effect of temperature increase on shear strength is a subject of controversy. Many studies indicate that an increase in temperature strengthens the clay. On the other hand, there are also studies that indicate an increase in temperature may cause a slight reduction in clay strength. Another significant effect of temperature change is the way it influences the consolidation state of the soil. By examining the previous studies, it is found that the preconsolidation pressure decreases as the soil temperature increases.