铁路沿线下导风板对风沙流场的控制规律

Control Law of Lower Air Deflector for Sand Flow Field along Railway

为了揭示风沙地带铁路沿线下导风板输沙工程措施对线路过境风沙流的输导效果及其控制机理,基于CFD(Computational Fluid Dynamics)的计算原理,采用三维数值计算分析方法并结合下导风板输沙的现场实测数据,分析下导风板对风沙流场的控制规律。结果表明:下导风板的输沙能力在风速较大(大于12m·s-1)时有较好效果,且前倾式下导风板的输沙能力明显强于直立式下导风板。现场实测也表明:采用前倾式下导风板输沙措施后,会在线路上形成较大的强风区(作用区),使线路迎风断面的各部位年积沙量均有显著减少,线路道心积沙量减少56%,下导风板前积沙量减少44%,下导风板后积沙量减少36%;现场实测结论与数值计算规律一致。建议在处于风沙区的铁路沿线采用下导风板治理铁路沙害时,要因地制宜并考虑当地的风况(风向、风速变化)特点进行下导风板工程的布置,才能取得较好的风沙输导功效。

In order to reveal the transport effects and control mechanisms of the lower air deflector on the wind-driven sand conveyance engineering measures along railway line in sandy area,and according to the three-dimensional numerical analysis and the measured data of the sedimentation of lower air deflector,the control rules of the lower air deflector were analyzed in detail based on CFD（Computational Fluid Dynamics）calculation principle.Results show that the sediment transport capacity of the lower air deflector has better effect at higher wind speed（more than 12 m·s-1）.Moreover,the sediment transport capacity of the forward inclined lower air deflector is obviously stronger than that of vertical lower air deflector.Field measurements also show that after using the sediment transport measure with forward inclined lower air deflector,a stronger gale zone is formed on the road（action area）.The annual sediment deposition in each section of the windward section of the line is significantly reduced.The amount of sediment in the line decreases by 56%,the amount of sediment before the lower air deflector decreases by44% and the amount of sediment behind the lower air deflector decreases by 36%.The measured results are consistent with the numerical ones.It is suggested that the lower air deflector be adopted to control railway sand disaster along the railway line in sandy area.The layout of the lower air deflector should be in accordance with the local conditions and take into account the local wind conditions（wind direction and wind speed changes）characteristics,in order to achieve better transport effect of aeolian sand.