随着列车速度的不断提升，列车由明线驶入隧道所引发的微气压波问题变得日益突出，组合型式缓冲结构较单一型式缓冲结构能更好的缓解微气压波的影响，为了进一步减缓微气压波对隧道周边环境的影响，提出了台阶开孔式组合型缓冲结构。基于κ-ε两方程紊流模型（κ为湍动能，ε为耗散率），运用数值模拟的方法，从开孔距离、开孔率、开孔数量、开孔位置4个方面进行研究，对列车驶入隧道所引起的初始压缩波压力和压力梯度值进行具体分析，得出优化设计参数。台阶开孔式缓冲结构对初始压缩波压力最大值的影响较小，但对初始压缩波压力梯度值影响较大。当开孔距离为4 m、开孔率α为36%、开孔数量为2孔、开孔位置为顶部开孔时，为最优工况，对压力梯度的减缓效果达到了60.14%。

The problem of micro-pressure waves caused by the high-speed train passing through the tunnel from the open line become more and more serious with the increase of the train speed. The combined buffer structure can better mitigate the impact of micro-pressure waves than the single type of buffer structure. In order to further alleviate the impact of micro-pressure waves on the surrounding environment of the tunnel, a buffer structure named ladder ventilation type combined buffer structure was proposed. Based on the standard κ-ε two-equation turbulence model (κ is the turbulent kinetic energy, ε is dissipation rate) and the numerical simulation method, four ventilation window parameters were studied, including the ventilation distance, the ventilation ratio, the number of ventilation windows, and the position of ventilation windows. The initial compression wave pressure and pressure gradient caused by the train entering the tunnel with different ventilation windows were analyzed, and the optimum parameters of the combined buffer structure were obtained. The buffer structure has less impact on the maximum pressure of the initial compression wave, but more impact on the initial compression wave pressure gradient. When the ventilation distance is 4 m, the ventilation rate α is 36%, the number of ventilation windows is 2, and the position of ventilation windows is the top ventilation, it is the optimal working condition, and the mitigation effect on pressure gradient reaches 60.14%.