On the modelling of thermo-active diaphragm walls based on monitoring data

In this contribution, some issues are addressed that concern the definition of a model for the numerical analysis of a thermo-active diaphragm wall. Given that a refined modelling could benefit from the knowledge of the actual behaviour of a real scale structure, a monitoring programme was planned and the research was then focused on the calibration of the thermal problem on the basis of on-site data. These data could provide insights into the energy performance and the thermal response of the diaphragm wall and the soil mass, and allowed for a better understanding of the process of heat transfer. The interpretation of the monitoring data contributed to the definition of the thermal boundary conditions at the ground surface and at the excavation side. Moreover, the condition at the excavation side was recognized as a major factor of influence of the heat transfer process, governing the direction of the heat flux in the different seasons of operation of the geothermal system. The calibration of the soil thermal properties remains an open issue, since the interpretation of the monitored temperatures at positions embedded in the soil is complicated by the influence of several uncertain factors.