Revision of Calculation Model for Micro-pressure Wave at Tunnel Portal of High Speed Railway
The micro-pressure wave significantly increases with the increase of train speed,which may affect the surrounding buildings and residents.The micro pressure wave at the tunnel portal is closely related to the pressure gradient of the first wave of the pressure wave inside the tunnel.Based on the actual vehicle test data,the pressure gradient at different positions inside the tunnel was analyzed,and the radiation solid angle(RSA)model was modified.The method for determining the spatial solid angle,a key parameter of the model,was provided.The results indicate that when the train passes through a ballastless track tunnel at a speed of 350 km/h,the pressure gradient of the first wave of the pressure wave gradually increases from the tunnel entrance to the tunnel center.The random forest method was used to analyze the parameter feature weights of the RSA model.The modified RSA model has a higher calculation accuracy for the peak micro pressure wave at the tunnel portal compared to the original RSA model.Three methods for measuring and calculating the spatial solid angle of tunnel openings by equipments such as drones or rangefinders have been proposed.