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A platform for research: civil engineering, architecture and urbanism
Stresses and deformations induced by geothermal operations of energy tunnels
Highlights Geothermal operations of energy tunnels markedly impact their mechanics. Thermally induced stresses within energy tunnels can be very significant. Thermally induced displacements within and around energy tunnels are negligible. Both compressive and tensile stresses develop in tunnels for heating or cooling. Serviceability limit state verifications must consider thermally induced effects.
Abstract Underground tunnels used as heat exchangers in the form of energy tunnels can sustainably meet the thermal energy needs of buildings across city districts. Recently, a considerable understanding of the energy performance of such earth-contact structures has been achieved. However, knowledge of the geotechnical and structural performance of energy tunnels associated with their geothermal operation has remained limited, despite its key role for reliable tunnel applications. This paper focuses on the geotechnical and structural performance of energy tunnels by providing a comprehensive analysis of their mechanics in the context of geothermal operations. Attention is devoted to the stresses and deformations that develop within and around energy tunnels due to the influence of temperature variations. Through 3-D thermo-hydro-mechanical finite element simulations, the following results are unraveled: (i) the mechanics of tunnels operating as heat exchangers is governed by the internal airflow conditions to such structures, the air-tunnel-soil temperature differential, and the tunnel-soil stiffness ratio; (ii) thermally induced stresses in energy tunnels can be significant, while thermally induced displacements are negligible; (iii) the conventional belief that heat extraction operations dominantly involve tensile stresses and heat injection operations pervasively cause compressive stresses is not always valid for energy tunnels due to the influence of internal airflows.
Stresses and deformations induced by geothermal operations of energy tunnels
Highlights Geothermal operations of energy tunnels markedly impact their mechanics. Thermally induced stresses within energy tunnels can be very significant. Thermally induced displacements within and around energy tunnels are negligible. Both compressive and tensile stresses develop in tunnels for heating or cooling. Serviceability limit state verifications must consider thermally induced effects.
Abstract Underground tunnels used as heat exchangers in the form of energy tunnels can sustainably meet the thermal energy needs of buildings across city districts. Recently, a considerable understanding of the energy performance of such earth-contact structures has been achieved. However, knowledge of the geotechnical and structural performance of energy tunnels associated with their geothermal operation has remained limited, despite its key role for reliable tunnel applications. This paper focuses on the geotechnical and structural performance of energy tunnels by providing a comprehensive analysis of their mechanics in the context of geothermal operations. Attention is devoted to the stresses and deformations that develop within and around energy tunnels due to the influence of temperature variations. Through 3-D thermo-hydro-mechanical finite element simulations, the following results are unraveled: (i) the mechanics of tunnels operating as heat exchangers is governed by the internal airflow conditions to such structures, the air-tunnel-soil temperature differential, and the tunnel-soil stiffness ratio; (ii) thermally induced stresses in energy tunnels can be significant, while thermally induced displacements are negligible; (iii) the conventional belief that heat extraction operations dominantly involve tensile stresses and heat injection operations pervasively cause compressive stresses is not always valid for energy tunnels due to the influence of internal airflows.
Stresses and deformations induced by geothermal operations of energy tunnels
Rotta Loria, Alessandro F. (author) / Di Donna, Alice (author) / Zhang, Manlu (author)
2022-02-20
Article (Journal)
Electronic Resource
English
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