Thermal- Structural Coupling Characteristic Analysis of Shield Energy Tunnel Under Design Condition

EasyChair Preprint no. 13594

Abstract

As society grows and energy demand rises, using subway source heat pumps to tap into shallow geothermal energy for cooling or heating is an effective solution. This turns shield tunnels into energy tunnels. Still, the impact of heat exchanger operation on tunnel structures needs more study. This paper uses COMSOL Multiphysics to examine the heat exchange in energy tunnels and the structural responses of shield tunnel segments. The results indicate that the performance of precast CHE in energy tunnels is excellent. A single-ring energy tunnel can provide cooling and heating capacities of 601.62W and 466.28W, respectively, during the cooling and heating seasons, with heat transfer efficiency of 63.46W/m² and 49.19W/m² respectively. The operation of the CHE during the cooling season leads to elongation of the tunnel segments, while during the heating season, compression of the tunnel segments occurs. The maximum tensile stress and maximum compressive stress generated in heating season are 0.60 MPa and 0.73 MPa respectively, while in cooling season they are 0.56 MPa and 0.87 MPa respectively. The compressive stresses generated during the cooling and heating seasons due to CHE operation are far below the compressive limit of C50 concrete, with tensile stresses representing 33% and 23% of the axial tensile strength, respectively. The calculation results indicate that under the design conditions of the heat pump unit, when the heat exchange between the CHE and the tunnel reaches steady state, the impact of CHE heat exchange on the structural integrity of the shield tunnel is relatively minor.

Keyphrases: Capillary heat exchanger, Energy tunnel, heat pump, Thermal-structural coupling

@Booklet{EasyChair:13594,
  author = {Shouheng Shen and Hui Zhang and Xinru Wang and Yongming Ji and Songtao Hu},
  title = {Thermal- Structural Coupling Characteristic Analysis of Shield Energy Tunnel Under Design Condition},
  howpublished = {EasyChair Preprint no. 13594},

  year = {EasyChair, 2024}}