Experimental Investigation of Energy Pile Response for Bridge Deck Deicing Applications-Article

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The study examined whether energy piles—deep foundations equipped with fluid-circulation loops—could provide geothermal heat for bridge-deck deicing without a heat pump. Full-scale field tests at Virginia Tech connected an instrumented, 30.4 m micropile to a prototype bridge deck. The system extracted ground heat during winter and returned heat to the ground during summer.<br /><br />During winter tests, the deck stayed above freezing with circulation tubes spaced 30 cm apart; closer 20 cm spacing kept the deck snow-free during a storm. Summer heat-injection tests demonstrated the potential to recharge the ground for later use.<br /><br />Thermal cycling also produced axial loads in the pile. Cooling during heat extraction generated tensile loads, while heating during recharge generated compressive loads. The largest measured tensile load was 170 kN at 6 m depth, and the largest compressive load was 125 kN. Load patterns were influenced by the pile’s steel casing and surrounding soil; the stiff cased section experienced concentrated stresses. Loads and temperature changes generally diminished after operations stopped, but recovery was sometimes incomplete before the next cycle.<br /><br />The authors conclude that energy piles can deice bridge decks without a heat pump, potentially reducing reliance on corrosive salts and costly separate geothermal infrastructure. Successful design requires matching deck heating demand to the capacity and spacing of energy piles, while accounting for thermally induced stresses and soil–pile interaction. Further research is needed on long-term, seasonal cycling and performance under structural loading.

Keywords

energy piles

bridge-deck deicing

geothermal heat

micropile

fluid-circulation loops

winter heat extraction

summer heat injection

thermal cycling

axial loads

soil-pile interaction