Selection of outside design temperature for predicting temperature inside railway tunnel in the hottest month in summer

Taking the long single track tunnel as a study object, establishes a calculation model of air temperature in the tunnel, discretizes the equations by the finite volume method, and developes a simulation program for air temperature in tunnel with MATLAB. Calculates the air temperature in the tunnel in the hottest month in summer by numerical simulation respectively with three different outside design temperatures, including the outdoor design temperature for summer ventilation (ODT), the average of monthly average temperature in the hottest months in recent 20 years (ATH) and the outside hourly typical temperature (OHT), and obtains the patterns of the air temperature distribution and the highest temperature change in the tunnel. The results show that if the ATH is adopted, the highest air temperature in the tunnel can be predicted more accurately.