为推进中国高速铁路隧道技术标准深化研究，开展400 km/h隧道结构设计参数的研究工作，而隧道净空面积为其中的一项重要内容。为尝试从列车内部瞬变压力角度得到400 km/h高速铁路隧道净空面积，建立基于舒适度标准的高速铁路隧道净空面积确定方法，以控制工况为基础，通过计算和分析，从列车密封性能方面讨论维持现有隧道净空断面的可能性，并研究提出400 km/h隧道净空断面建议值。主要结论有： 1）现有350 km/h单线隧道以400 km/h运营时，列车动态密封指数最低为22 s，车内瞬变压力超标的可能性较大； 2）400 km/h单、双线隧道净空面积建议值分别为85 m2和100 m2，对应的列车动态密封指数最低为18 s，更加符合现有标准对列车密封性能的要求，车内瞬变压力超标的可能性大幅降低； 3）提出的400 km/h高速铁路隧道净空面积建议值和对应的密封性能要求可为有关标准、规范的制订提供参考。

The research on structural design parameters of 400 km/h highspeed railway tunnel is being carried out in order to promote the technical standards of highspeed railway tunnels in China, and in which the tunnel clearance area is one of the key items. The method for determining the clearance area of highspeed railway tunnel on the basis of passenger ear comfort standard is established from the aspect of rail vehicle internal transient pressure. Based on the control condition, the probability for maintaining existing tunnel clearance area is discussed in terms of rail vehicle airtightness by calculation and analysis. And the suggested clearance area of 400 km/h tunnel is proposed. The conclusions are drawn as follows: (1) The lowest train dynamic airtightness index is 22 s when the existing 350 km/h singleline tunnel operates at a speed of 400 km/h, and the rail vehicle internal transient pressure exceeds the passenger ear comfort standard may be a high probability event. (2) The suggested clearance areas of singleline and doubleline 400 km/h tunnels are 85 m2 and 100 m2 respectively, and the corresponding train dynamic seal index is 18 s, which is more reasonable to the existing train and therefor the risk of exceeding standard can be greatly reduced. (3) The suggested clearance area for 400 km/h highspeed railway tunnels and corresponding airtightness requirements can be taken as the reference for relevant standards and specifications.