Ground temperature distribution and evolution of Lanzhou subway in the Chinese Loess Plateau

Abstract

The temperature field of the subway stratum is a consequential basis for adjusting the thermal environment in the subway. In this paper, the initial ground temperature of Lanzhou subway in the Loess Plateau was measured, and the temperature field evolution of the surrounding rock in the subway tunnel was explored under operational conditions. The results show that in the initial ground temperature field, the annual variable temperature layer of the subway is located at the surface to the depth of 12 m, with a sinusoidal distribution and a phase lag phenomenon. The lag time of the initial ground temperature at 11 m depth is about 80 days compared with the initial ground temperature at 1 m depth. The annual constant temperature layer is located below the depth of 12 m with a temperature of 15.2 °C. Moreover, the air temperature has the greatest influence on the heat exchange between the air and surrounding rock. The heat flux is negatively correlated with the heat exchange time, while positively correlated with the low water content and air temperature. However, the tunnel shape and high water content have little effect on the variation in heat flux, which is less than 0.1 W/m2.

Keywords

• Lanzhou subway
• Thermal environment
• Ground temperature
• Heat exchange
• Chinese loess plateau