CENTRIFUGE SIMULATION OF THE THERMAL RESPONSE OF A DRY SAND-EMBEDDED DIAPHRAGM WALL

Geothermal heat exchangers buried in diaphragm walls as an alternative of renewable energy sources can be quite competitive with shallow geothermal resources. The thermal response of a diaphragm wall embedded in the sand foundation under thermomechanical coupling conditions was followed in laboratory centrifuge tests. The model of exchanger tubes enclosed in the diaphragm wall embedded in the sand foundation accounts for lateral loading on the wall simulated by 1 and 50g acceleration conditions in the centrifuge. Thermal loading, mechanical unloading, and thermomechanical coupling tests were carried out separately. The temperature, deformation, and soil pressure on the wall were monitored. The deformation and thermal stress along the cantilever wall were verified by numerical simulation. The thermal stress on the wall was revealed to be larger than the excavation-induced one. The maximum thermal stress was observed near the bottom of the wall. Though the wall was embedded in surrounding soil, heating caused accumulation of thermal stresses induced by temperature variations, which should be seriously considered in the heat exchanger design for cantilever walls of building structures.