Tunnels, a New Potential Source of Energy: 3D Modeling of a Heat Exchanger within Tunnel Lining

C. Soussi [1], O. Fouché [2], G. Bracq [3], S. Minec [3],
[1] Le Cnam, Paris, France
[2] Ecole des Ponts, Champs-sur-Marne, France
[3] Bouygues Construction, Saint-Quentin-en-Yvelines, France
Published in 2016

This work investigates the possibility of thermal activation of future tunnels to heat and/or cool the surface buildings or infrastructure such as subways stations. The principle is to insert pipes in the tunnel lining segments, which are connected to a geothermal pump. A heat transfer fluid antifreeze circulates inside the tubes to exchange heat with the surrounding environment (tunnel air and surrounding rock). The thermo-hydraulic problem is investigated with a complete 3D finite element model. This model is employed to realize comparative and parametric studies which analyze the influence of fluid properties and ground thermal properties on the effectiveness of the exchange system and the thermal equilibrium of the surrounding soil. The influence of groundwater is also studied.