Thermal pressure ventilation analysis in a sloping high-temperature tunnel: A case study in China

Heat damage in tunnels is an increasingly prevalent issue, particularly in deeply buried tunnels. Thermal pressure ventilation cannot be ignored in high-temperature inclined tunnels. Implementing appropriate thermal pressure ventilation can lead to substantial energy savings. To achieve this outcome, this study proposes a novel calculation model that integrates analytical solutions for the surrounding rock temperature with discrete solutions for the airflow temperature. The maximum relative prediction error is only 6.9 %. By employing this proposed calculation model, this study analyzes the impact of the ventilation time, environmental temperature, tunnel slope, and tunnel surface roughness on the thermal pressure ventilation dynamics while also analyzing the energy savings potential. This research revealed a negative correlation between ventilation time and environmental temperature with thermal pressure ventilation, while a positive correlation was observed with tunnel slope. Tunnel roughness has a marginal influence on thermal pressure ventilation. For the Nige Tunnel (a high-temperature tunnel with a 2 % slope), the airflow temperature within the tunnel can be effectively lowered to meet the cooling requirements of 28 °C after 407 days of thermal pressure ventilation. The energy-saving analysis demonstrated that thermal pressure ventilation could yield savings of 275 MW·h in the first year, reducing carbon emissions by 23.0 tons. This study provides theoretical guidance for the thermal pressure ventilation of high-temperature inclined tunnels and offers a novel model for thermal pressure ventilation calculations.