Abstract:

In order to improve the thermal environment of the deep-buried tunnels, and master the thermal and humidity variation law during the flow of air through the tunnel, the unsteady heat transfer model of air flow and surrounding rock was constructed by the method of field measurement and theoretical deduction, and the model was verified by the field measurement data. Based on the above theoretical model, the influences of ventilation duration, wind speed in the tunnel section and supply air temperature and humidity on the ambient temperature and humidity of the tunnel and the comprehensive heat transfer coefficient(CHTC) were quantified, and the critical time of effective ventilation and cooling and section critical wind speed were obtained by numerical inversion. The results show that when the ventilation duration τ>900 h, the CHTC does not change with the ventilation time; it indicates that the cooling effect cannot be achieved in the ventilation time domain. In the range of u<0.22 m/s, isotherm and isolative humidity line are dense, indicating that the temperature gradient and humidity gradient of the airflow change significantly in this flow velocity section, and the heat and humidity transfer caused by temperature difference and concentration difference is strong. At this time, increasing the air supply volume is conducive to reducing the ambient temperature and humidity of the tunnel. The research results provide an important theoretical basis for the ventilation and cooling of deep-buried construction tunnels.

Key words: deep buried construction tunnel, unsteady heat transfer, air flow, thermal parameter, temperature and humidity, thermal environment, heat and moisture transfer