Study on ambient temperature and humidity in the construction tunnel under the influence of ventilation and hot water gushing

The influx of hot water will intensify the detrimental effects of heat and humidity during the excavation of high geothermal tunnels. The spatiotemporal evolution of the ambient temperature-humidity field in the construction tunnel under the coupling action of ventilation and hot water is critical. Based on the theory of heat and mass transfer, a numerical model was developed to simulate the temperature and humidity conditions within a construction tunnel. The model considers the coupling effects of heat and moisture between airflow, hot water, and the surrounding rock. The distribution of temperature and humidity in the tunnel was analyzed, and the study investigated the influence mechanisms of ventilation volume (Va) and water gushing conditions on the ambient temperature and humidity in the construction tunnel. The main conclusions include: (1) During tunnel construction, the airflow temperature (Ta) and relative humidity (RH) varied as follows: heating and humidifying, constant humidity heating, and constant humidity cooling. (2) Altering the water temperature (Tw) will affect the distribution pattern of RH from the working face to the tunnel portal. Similarly, modifying the length of the ditch without the cover plate (Lc) will impact the distribution trend of Ta and RH. (3) When the Va affects the RH mainly through the airflow velocity rather than the evaporation coefficient, the linearity between the Va and RH is weak. Water volume and Tw both impact the humidity distribution by altering the amount of heat needed for evaporation. (4) Given the significance of the impact of individual factors on the temperature and humidity, it is advised that the Ta and RH be regulated by increasing the Va and decreasing the Lc, respectively. The research can give direction for temperature and humidity control in a tunnel where hot water gushes during construction.