Along with the rise of train speed, the protection effect of earth type wind barrier needs to be im proved. The method of further heightening the top of the original wind barrier was considered. Based on three di mensional steady, uncompressible N - S equations and standard k - e equations, and using box car as the repre sentative model, when the crosswind speed is 50 m/s and the train speed is 120 km/h, the aerodynamic forces of box car running behind symmetrical and un - symmetrical earth type wind barriers with different increase height were simulated. The overturning moment was used as evaluation index to analyze the influence of increased height on aerodynamic performance of the box car. The result proves that partially heightening the top of earth type wind barrier can effectively improve its protection effect. The reasonable increasing height of symmetrical earth type wind barrier is 0. 28 m. For un - symmetrical type, the reasonable increasing height is 0. 62 m when its windward side height is lm, and the reasonable increasing height is 0.49 m when its windward side height is 2 m. Therefore, the results provide the theoretical basis for the engineering practical application.%随着兰新线上通过列车速度的提高,现有土堤式防风墙的防护效果亟需改善,考虑在原有挡风墙顶部进行局部加高改造.基于三维定常、不可压N-S方程与к-ε双方程湍流模型,采用棚车为代表车型,在横风风速为50 m/s时,分别对不同加高高度的对称和非对称土堤式挡风墙条件下运行速度为120 km/h的货物列车所受气动力进行了数值模拟,以车辆倾覆力矩为考核指标分析挡风墙加高高度对棚车气动性能的影响.研究结果表明,在现有土堤式挡风墙顶部局部加高能有效地提高其对列车的防风作用；其对称土堤式挡风墙合理加高高度为0.28 m,迎风侧高度1 m和2 m的非对称土堤式挡风墙合理加高高度分别为0.62和0.49 m.结果为工程实际应用提供了理论依据.
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