Investigation on heat transfer performance of energy diaphragm walls under groundwater flow condition

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The flow of groundwater affects the transport of heat, subsequently impacting the heat transfer performance of energy diaphragm walls. To investigate the effect of groundwater flow on the thermal performance of energy diaphragm walls in the actual project, a three-dimensional finite element model of the thermo-hydro coupling was established. This model's accuracy was confirmed using in-situ experimental data. Subsequent analyses explored the influence of groundwater flow velocity on the long-term heat transfer efficiency of energy diaphragm walls and the temperature field distribution in both the wall and adjacent soil during winter/summer cyclical operations. Studies have shown that the increase of groundwater flow velocity can promote the migration of heat accumulated in the wall and in the soil around the wall to a position farther away from the wall along the flow direction, thereby promoting the long-term heat exchange efficiency of the thermo-active diaphragm walls. Moreover, as winter and summer operating conditions transition, the previously accumulated heat in the wall and surrounding soil aids in boosting the current mode's heat exchange efficiency. In addition, groundwater flow also facilitates the movement of heat accumulated at the bottom of the excavation face, allowing the ground's temperature field to stabilize faster. This indirectly bolsters the heat exchange efficiency of the energy diaphragm walls. The research results may enrich the understanding of the heat transfer behavior of energy diaphragm walls under actual working conditions.