Modelling Thermo-active Diaphragm Walls

Thermo-active geotechnical structures do not only ensure structural stability but also enable to provide thermal needs, throughout heating or cooling the structure. Thermo-active piles are now a widely used technology. But the idea of using geotechnical structures as heat exchanger is also possible for diaphragm walls. Such a choice has been made in Vienna, but also in Rennes and currently Paris metropolitan underground stations. Whereas modelling of energy piles is now well-known, the behaviour of thermo-active diaphragm walls appears more complex to deal with. The present article proposes elements of methodology in order to take into account contraction and dilatation caused by temperature changes for such structures, based on numerical analysis. An analysis of the results is then performed, and allows to identify the major phenomena and their order of magnitude.