Influence of piston airflow and mechanical airflow on cooling effect of high-geothermal tunnels: a pilot study

• Published in: Journal of thermal analysis and calorimetry Vol. 148; no. 13; pp. 6151 - 6167
• Main Authors: Zeng, Yanhua, Tao, Liangliang, Luo, Mingrui, Ye, Xuqian, Yuan, Yanping
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.07.2023; Springer; Springer Nature B.V
• Subjects: Air flow; Ambient temperature; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Cooling effects; Damage; Entrances; Heat; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Temperature distribution; Tunnels; Ventilation; Natural wind; Piston airflow; Mechanical airflow; High-geotemperature tunnel; Ambient temperature
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-023-12163-8

Controlling the ambient temperature inside a tunnel to less than 28 °C is the key to ensure safe operation of tunnels that experience high-geothermal temperature. One of the most popular methods to lower the ambient temperature of an extra-long tunnel with high-geothermal temperature is mechanical ventilation. Taking the Layue tunnel as an example, this paper examined the impact of natural wind, piston airflow, and mechanical ventilation on tunnel thermal hazard control. The results show that the cooling effect of natural ventilation is better when natural wind flows from entrance to exit than when it blows from exit to entrance. When there is only natural ventilation, the length of tunnel ambient temperature higher than 28 ℃ is more than 15 km within 5.0 years of natural ventilation. Piston airflow does not significantly reduce the length of high tunnel ambient temperature distribution range. Only relying on natural wind and piston airflow cannot control heat damage in the Layue tunnel. The thermal layer can reduce the length over which high tunnel ambient temperature is distributed, but the maximum reduction is within 2500 m. When the mechanical airflow speed is at least 3.0 m s −1 , the heat damage can be effectively controlled within one year. Whether mechanical airflow is started in summer or winter, mechanical airflow shall be carried out at the speed of 3.0 m s −1 at least 200 days in advance to effectively control the heat damage of Layue tunnel.