Thermal and structural performance of energy tunnels

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Thermal performance assessment of an energy lining for the Lyon-Turin base tunnel

The use of geothermal energy for heating and cooling purposes is an environmentallyfriendly and cost-effective alternative with the potential to replace fossil fuels and help to mitigate global warming as well. The paper illustrates the geothermal potential evaluation of a portion of the Lyon-Turin base tunnel considering the thermal activation of the tunnel concrete segmental lining. The international infrastructure will connect Italy to France, crossing the Alps and meeting uncommon climate conditions, reaching a peak temperature of 47  C, due to its significant rock overburden (up to 2500 m) under the Ambin massif. A thermo-hydraulic numerical model was used to simulate the heat exchange of the system and quantify the power achievable by thermally activating a 10 km-long section of the base tunnel. Sensitivity analyses were performed to investigate the influence of the heat carrier fluid and the air flow velocities as well as the inlet temperature on the heat exchange. Moreover, four different operational conditions were compared to allow for assessing the overall thermal performance of the energy lining in terms of heat exploited and of the capacity of cooling the tunnel

Thermal performance of a metro station in Turin equipped with energy geostructures

High pollution levels combined with the lack of green spaces are hitting many cities leading to the exploitation of the underground for transportation. Given the need to foster local energy sources with low environmental impact, energy geostructures are more and more being explored. In this context, the promising outcomes of the experimental campaign on the thermal activation of tunnel segments carried out on Turin ML1 South Extension encouraged the authors to investigate applicability of energy geostructures for Turin ML2 project. This paper is intended to focus on the understanding of the thermo-hydraulic behaviour of a metro station equipped with energy diaphragm walls. A 3D FE numerical model reproducing the layout of the planned Mole-Giardini Reali station is used to study the energy exchange potential of the thermoactive walls. The quantification of the exploitable energy to meet the user demands of the station and of buildings above will be discussed on the basis of the results obtained

Capitolo 6 - Valorizzazione del calore del terreno

Documento elaborato dal gruppo di lavoro GESTAG (GEstione SosTenibile delle Acque nelle Gallerie), istituito il 20/06/2012 dal Comitato Italiano dell’Associazione Internazionale degli Idrogeologi. Questo documento è stato approvato dal Consiglio Direttivo del Comitato Italiano di IAH in data 09/07/2020

Multi Scale Numerical Modelling Related to Hydrofracking for Deep Geothermal Energy Exploitation

Prediction of fracture propagation through rock masses is investigated in this paper by adopting the Distinct Element Method (DEM) and the Voronoi tessellation. A microstructure-based model was created. Microparameters governing Voronoi sub-blocks contacts behaviour were calibrated against laboratory tests results for different rocks. An upscaling procedure is proposed to build reliable and representative numerical models at in situ scale to study fracture propagation for deep geothermal wells

Early-warning debris flow and avalanches detection system based on optical fiber polarization sensing

Landslides, avalanches and debris flows are the main hazards in the mountain environment, endangering people and infrastructures. The existing monitoring systems in the geotechnical field are often unsuitable for real-time applications, such as early-warnings of the aforementioned events. We present an optical fiber system able to give an alarm when some anomalous event is detected. Experiments have been carried on a reduced scale model of a slope of a mountain, showing that state of polarization monitoring is a reliable way to early-detect anomalous vibrations