Soils surrounding energy tunnels are often unsaturated, particularly in areas with a low water table. All studies of the mechanical behaviour of energy tunnels focused on saturated or dry soils. Through numerical simulations using a coupled thermo-hydro-mechanical model for unsaturated soils, this study aims to improve the understanding of the interactions between energy tunnels and unsaturated ground. The influences of water table position and soil type on the mechanical behaviour of energy tunnels were investigated. Results show that the thermally-induced lining convergence of energy tunnels does not change much with the water table position. Nevertheless, the other mechanical responses (e.g., settlements of ground and tunnel and lining stress changes) highly depend on the water table position. These mechanical responses are more significant when the water table is higher than the tunnel center, except for the larger settlements at a lower water table in clay. Furthermore, the above responses are underestimated if soils above the water table are assumed to be completely dry. The degree of underestimation is most significant for the clay, followed by silt and sand, e.g., a maximum of 54%, 23% and 10% in the change of circumferential stress, respectively. These results highlight that the unsaturated soil model should be used to evaluate the thermo-hydro-mechanical responses of energy tunnels in unsaturated soils, particularly for the clay ground.

中文翻译：

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非饱和土中能量隧道的热-水-力学行为


能量隧道周围的土壤通常不饱和，特别是在地下水位较低的地区。所有关于能量隧道力学行为的研究都集中在饱和或干燥的土壤上。通过使用非饱和土的热-水-力学耦合模型进行数值模拟，本研究旨在提高对能量隧道与非饱和土之间相互作用的理解。研究了地下水位位置和土壤类型对能量隧道力学行为的影响。结果表明，能量洞热致衬砌收敛性随地下水位位置变化不大。然而，其他机械响应（例如地面和隧道的沉降以及衬砌应力变化）很大程度上取决于地下水位位置。当地下水位高于隧道中心时，这些机械响应更为显着，但较低地下水位粘土中较大的沉降除外。此外，如果假设地下水位以上的土壤完全干燥，则上述响应会被低估。粘土的低估程度最为显着，其次是粉砂和砂，周向应力变化最大分别为54%、23%和10%。这些结果强调，非饱和土模型应用于评估非饱和土中能量隧道的热水力学响应，特别是粘土地基。