Thermoactive geostructures are considered an economically suitable and environment-friendly solution for heating and cooling buildings. Energy tunnels have gained growing interest in recent years because of the large ground volume involved in heat exchange in comparison to building foundations. Heat exchange is obtained by embedding a circuit of pipes into the precast concrete lining, resulting in a reduction of the initial costs of installation with respect to standard low-enthalpy geothermal solutions. In this paper, thermal activation of the twin tunnels of the II line of Warsaw metro, Poland, is considered with the aim of evaluating the geothermal potential of the line. Thermohydraulic finite-element analyses were performed on a number of representative cross-sections, considering site-specific hydrogeological conditions based on the Engineering Geological Database of the Capital City of Warsaw. Results demonstrate that the thermal activation of the two 1·6 km-long tunnels could exchange up to 5·3 and 5·8 GWh in the heating and cooling seasons, respectively. Furthermore, the influence of the local geological conditions on the exchangeable heat rate was investigated. The results form a basis for a preliminary assessment of the shallow geothermal energy utilisation potential for the design of further extensions of the metro line in Warsaw.

中文翻译：

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NE延伸华沙（波兰）地铁隧道的地热潜力

热活性地质结构被认为是用于加热和冷却建筑物的经济上合适且环境友好的解决方案。近年来，由于与建筑基础相比，热交换涉及的地面体积较大，因此能源隧道引起了越来越多的兴趣。通过将管道回路嵌入预制混凝土衬砌中来实现热交换，从而相对于标准的低焓地热解决方案，降低了安装的初始成本。在本文中，考虑对波兰华沙地铁II号线的双隧道进行热活化，以评估该线的地热潜力。对许多有代表性的横截面进行了热工液压有限元分析，根据华沙首都工程地质数据库，考虑特定地点的水文地质条件。结果表明，在供暖和制冷季节，两条1·6公里长的隧道的热活化分别交换达5·3和5·8 GWh。此外，研究了当地地质条件对可交换热率的影响。研究结果为初步评估浅层地热能利用潜力奠定了基础，以进一步设计华沙地铁线。研究了当地地质条件对可交换热率的影响。研究结果为初步评估浅层地热能利用潜力奠定了基础，以进一步设计华沙地铁线。研究了当地地质条件对可交换热率的影响。研究结果为初步评估浅层地热能利用潜力奠定了基础，以进一步设计华沙地铁线。