Research on ventilation cooling design driven by human thermal response in high geothermal temperature tunnel construction

Constant high temperature conditions in tunnel not only significantly reduced the labor efficiency of workers but also affected their physical and mental health. However, the traditional design of ventilation and cooling for high geothermal tunnel construction only considers the control of environment temperature and ignores the thermal comfort state of the workers, which will increase the potential risk of tunnel safety accidents. Therefore, this paper adopted the methods of scene testing, theoretical analysis and numerical simulation to establish a modified evaluation model applicable to the thermal comfort of workers in high geothermal tunnels. By analyzing the temperature distribution pattern of heat-sensitive parts of workers engaged in different labor intensity under different air supply parameters, the design strategy for ventilation and cooling of high-temperature tunnels was refined on the basis of ensuring that the environment temperature and thermal comfort meet the requirements. The results show that ventilation design parameters that satisfy the environmental temperature control criteria are equally adequate for worker thermal comfort at light-intensity work. However, when the ambient temperature is higher than 40 °C, the thermal comfort of workers engaged in medium-intensity work still does not meet the requirements, even if the ambient temperature already meets the criteria. It is recommended that the wind speed be increased by at least 8.3 %, 15.6%and 28.6 % for ambient temperatures of 40 °C, 45 °C and 50 °C, respectively. More effective cooling techniques should be tried to further enhance thermal comfort for workers engaged in heavy workloads especially in hot environments exceeding 40 °C.