An innovative steel joint for driven geothermal energy piles-Poster Upload

Poster Upload

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The study presents an innovative steel joint that enables driven precast concrete piles to function as geothermal energy piles. Unlike bored and continuous-flight-auger piles, driven piles are manufactured in segments because of transport limits, making it difficult to connect heat-exchange (HE) loops securely across pile joints.<br /><br />The new Driven Energy Pile (DEP) joint adapts conventional steel pile joints with side channels for single or double HE loops. The loops pass through the joint and connect using standard fittings, while steel pins secure the joint. Two joint sizes were developed: 270 mm for a single loop and 350 mm for double loops.<br /><br />The joint’s performance was evaluated through impact, hydraulic pressure, and bending tests in line with relevant standards. Connected pile segments withstood 1,000 impacts without damage. After impact testing, the HE pipes were pressurized to 100 psi (689 kPa) for 90 minutes; no leakage or pressure drop occurred. In bending tests, the joints remained undeformed, and their capacity exceeded that of the concrete pile segments.<br /><br />The results indicate that DEP joints can provide a robust connection while preserving the integrity of the heat-exchange loops. This development could facilitate commercial use of driven precast concrete piles for building heating and cooling.

Keywords

driven precast concrete piles

geothermal energy piles

Driven Energy Pile (DEP) joint

heat-exchange loops

steel pile joint

single loop

double loop

impact testing

hydraulic pressure test

bending test