Centrifuge and numerical modelling of the thermomechanical behaviour of energy cantilever walls in sand

Energy diaphragm walls are a form of energy geostructure that have been demonstrated to have high heat exchange efficiency. The thermomechanical behaviour of energy walls subjected to thermal cycles has been studied mainly through numerical modelling over the past decade, yet quality data are severely lacking to validate the models to further understand the soil–wall interaction. In this study, centrifuge model tests were conducted to investigate the thermally induced structural responses of an energy cantilever wall embedded in a uniform sand bed of different densities, accompanied by numerical back-analysis. A transient peak in wall moment was identified during each heating–cooling cycle. This phenomenon occurred prior to reaching a steady-state thermal equilibrium due to the delayed responses of soil at a distance before the heating and cooling front arrived. This transient moment can be 7–16% higher than the steady-state value in each cycle, highlighting the importance of capturing the transient responses for safe wall design against the ultimate limit state. Significant ground surface total and differential settlement were induced by the thermal cycles, mainly within 2 times the excavation depth away from the wall. The cumulative settlement could exceed the serviceability limit state threshold for any foundation being built right behind the wall.