Response-surface-model based on influencing factor analysis of subway tunnel temperature

Abstract Subway tunnel temperature has the significant effects on the thermal environment in both tunnel and public station area. Taking good control of this parameter is meaningful for operating safely and effectively. However, the simulation of subway tunnel temperature is both complex and time-consuming. In this research, tunnel temperature was studied by numerical simulation. The three influencing factors concerning internal heat generation (passenger number, carriage weight, and Regenerative Braking System (RBS) efficiency), and two factors concerning transmission load (soil conductivity and thermal capacity) were analyzed. In order to figure out the overall effect of these five factors, a Response Surface Model (RSM) of the subway tunnel temperature was established by Box-Behnken design, and it is found that the response value of each experiment setup fits well with the simulated result. According to the RSM, if the passenger number, carriage weight, RBS efficiency, soil conductivity, and soil thermal capacity change from the possible minimum to maximum values, the tunnel temperature increases 3.34 °C, 1.76 °C, 9.26 °C, 1.02 °C, and 0.46 °C, respectively. Therefore, the passenger number and carriage weight have a positive impact on the tunnel temperature; the RBS efficiency, soil conductivity, and thermal capacity have a negative impact. RBS efficiency plays the most important role among the five factors. The response-surface model is an approximated mathematical model with multi-factors, it provides a quick way of predicting subway tunnel temperature in different situations, which could be helpful in both design and operation stages in subway.