我国铁路网络在西部山区的大规模建设已经启动，山区峡谷地形复杂，铁路沿线风速分布受到峡谷地形的影响，峡谷内部风速分布不均匀，列车在峡谷风场下跨桥隧运行气动载荷剧烈变化，导致轮轨作用力骤增，列车安全性降低，极端情况下甚至发生脱轨倾覆等不安全事故。常规的高速列车峡谷风工况数值模拟中使用恒定风场或者大气边界层指数风，与实际情况不符，与此同时，列车在峡谷风场下跨桥隧运行的气动特性与流动机理研究较少，更是鲜有列车跨桥隧运行动力学特性的研究。因此，有必要建立适用于山区峡谷的风场模型，对风场模型下列车跨桥隧运行的气动和动力学特性进行研究，在此基础上，建立高速列车山区峡谷运行的速度安全域，为山区铁路建设提供理论指导。围绕以上问题，本文开展了以下研究工作：

(1) 通过与山区实测风场数据的对比和网格无关性验证，确定了山区峡谷风场数值模拟的计算方法与网格配置。考虑山体壁面粗糙度，对典型峡谷风场进行了计算，分析了峡谷风场的流场特性；利用测点风速数据，理清了峡谷内竖直方向和水平方向的风速分布规律，通过指数拟合得到了二维峡谷风场数学模型；进一步地，分析了峡谷风场模型参数在峡谷内不同位置的分布规律和峡谷参数对风场模型参数的影响。该成果能够为高速列车山区跨桥隧运行提供更准确合理的风场边界条件。

(2) 通过与风洞试验数据的对比和网格无关性验证，确定了高速列车跨桥隧运行流体力学计算方法与网格拓扑结构。将峡谷风场模型作为列车跨桥隧运行的风场边界条件，采用重叠网格算法对列车跨桥隧运行进行了非定常计算。通过对列车在不同风场下流场特性和涡结构特性的分析，深入理解峡谷风场下高速列车跨桥隧运行的气动特性和流动机理。此外，对不同车速和风速工况下列车的气动特性进行了研究，明确了气动载荷随峡谷风速的变化规律。所得气动载荷结果可以为列车动力学计算以及安全性分析提供基础。

(3) 建立了三编组高速列车动力学模型并通过与文献结果的对比验证了其准确性。将各节车气动载荷作为激励施加在列车的动力学计算中，通过多体动力学计算，得到列车跨桥隧运行过程中的轮轨作用力时间历程，对比各轮对力值，找到了最危险轮对。将不同风速下最危险轮对的安全性指标进行拟合，得到了列车安全运行的临界风速。通过对比峡谷风场和均匀风场下列车安全性指标和临界风速，说明列车跨桥隧运行安全性研究中风场模型选择的重要性。进一步地，对不同车速和风速下的安全性指标进行多项式拟合，得到了列车峡谷风作用下跨桥隧运行的车速-风速安全域关系式。

(4) 开展了峡谷风作用下高速列车跨桥隧运行防风措施研究。在桥梁沿线两侧布置挡风墙结构，对比了有无挡风墙作用下列车的流场特性和气动载荷差异，从动力学角度对比了挡风墙对列车跨桥隧运行安全性指标和临界风速的的改进。此外，对挡风墙在峡谷桥梁上的安装位置进行了对比，探索挡风墙在列车跨桥隧运行过程中对动力学指标的影响机制。该成果能够为山区铁路防风减灾措施提供理论依据。

The large-scale construction of China's railway network in the western mountainous areas has been launched. The terrain of mountainous valleys is complex, and the distribution of wind speed along the railway is affected by the terrain of the valleys, resulting in uneven distribution of wind speed inside the valleys. Under the influence of the wind field in the gorge, the aerodynamic loads of the train when crossing bridges and tunnels change violently, causing a sudden increase in wheel-rail force, and reducing the safety of the train. In extreme cases, unsafe accidents such as derailment and overturning may occur. The numerical simulation of high-speed train in conventional gorge wind conditions uses constant wind field or atmospheric boundary layer wind exponent, which does not match the actual situation. At the same time, there is little research on the aerodynamic characteristics and flow mechanism of the train running across bridges and tunnels in the gorge wind field. Therefore, it is necessary to establish a wind field model suitable for mountainous gorge, and to study the aerodynamic and dynamic characteristics of the train running across bridges and tunnels under the wind field model. On this basis, the speed safety threshold of high-speed train running in mountainous gorge should be established to provide theoretical guidance for mountainous railway construction. Focusing on the above issues, this article conducted the following research:

(1) Through comparing with the measured wind data in mountainous areas and verifying grid independence, the computational method and grid configuration for numerical simulation of mountainous gorge wind field were determined. Considering the simulation of roughness function on rough wall surface, the typical gorge wind field was calculated, and the flow field characteristics of the gorge wind field were analyzed. Using the wind speed data at measurement points, the distribution laws of wind speed in vertical and horizontal directions inside the gorge were clarified, and a two-dimensional mathematical model of gorge wind field was obtained through exponential fitting. Furthermore, the distribution laws of parameters in different positions inside the gorge and the influence of gorge parameters on wind field model parameters were analyzed. The result can provide more accurate and reasonable wind field boundary conditions for high-speed train running across bridges and tunnels in mountainous areas.

(2) Through comparing with wind tunnel test data and verifying grid independence, the computational method and grid topology of high-speed train hydrodynamic force calculation were determined when it is running across bridges and tunnels. Taking the gorge wind field model as the wind field boundary condition for the train running across bridges and tunnels, an unsteady calculation was carried out using an overlapping grid algorithm. Through analyzing the flow field characteristics and vortex structure characteristics of the train under non-ventilation conditions, the aerodynamic characteristics and flow mechanism of high-speed train running across bridges and tunnels under gorge wind field were understood deeply. In addition, the aerodynamic characteristics of train at different speeds and wind speeds were studied, and the variation law of aerodynamic load with gorge wind speed was identified. The aerodynamic load result can provide a foundation for train dynamic calculation and safety analysis.

(3) A dynamic model of three-unit high-speed train was established, and its accuracy was verified through comparing with literature results. The aerodynamic loads of each car were used as excitation to impose on the dynamic calculation of the train. Through multi-body dynamic calculation, the wheel-rail force time history of the train running across bridges and tunnels was obtained, and compared with each wheel pair force value, the most dangerous wheel pair was found. The safety index of the most dangerous wheel pair under non-ventilation speed was fitted, and the critical wind speed for safe train operation was obtained. By comparing the train safety index and critical wind speed between gorge wind field and uniform wind field, it proves the importance of selecting wind field model in studying train safety in running across bridges and tunnels. Furthermore, polynomial fitting was carried out for safety indices at different speeds and wind speeds, and a relationship between train speed and wind speed safety threshold under gorge wind action was obtained.

(4) The study on measures to prevent wind damage and reduce train operation safety hazards under gorge wind action was conducted. The structure of wind barrier was arranged on both sides of bridges along the line to compare differences in flow field characteristics and aerodynamic loads between with and without wind barrier effect on train operation. From the perspective of dynamics, compared to evaluate the improvement of train operation safety indicators and critical wind speed with or without wind barrier protection measures. In addition, a comparison was made on the installation position of wind barrier on bridges in mountainous areas to explore its influence mechanism on dynamic indicators during train operation across bridges and tunnels. The result can provide a theoretical basis for wind damage prevention measures in mountainous railway construction.