基于室内外风洞试验的铁路风吹雪特性研究

Study on characteristics of snow-drifting in railway area based on indoor and outdoor wind tunnel tests

为了研究铁路路堑区域风吹雪作用下路基内外的风雪场分布特征,减少沉积在铁路路堑内的积雪量,基于新建铁路路堑和3种不同形式的防雪栅,在风吹雪灾害易发区域采用原状雪进行风洞试验。结合CFD多相流模型分析方法,建立与风洞试验相同的模型,得到路堑内外不同区域的流场分布变化规律。将试验结果与现场实际布设防雪栅区域的冬季积雪分布进行对比。研究结果表明:本文所采用的模拟试验与现场试验段积雪分布有较好的一致性,路堑内积雪平台的存在可以使得雪粒较多的沉积在积雪平台内,并增加路基表面风速,减少风吹雪作用下沉积在路基顶面的雪量;防雪栅主要影响路堑外流场分布,使雪粒沉积在栅栏两侧并抑制路堑边坡顶部的侵蚀作用;防雪栅与路基间的布置距离应当大于栅栏高度的10倍以上,防雪栅对流场的影响作用与栅栏高度呈非线性关系,而多排防雪栅作用下各排栅栏对流场的影响基本一致;增大风速会减小风雪平衡状态的自然雪深,使得路堑外更多的雪粒被吹向路堑内,路堑内结构形式会明显减弱流场流速,近地面雪粒在六级强风条件下依旧处于小于起动速度的状态,因此,来流风速越大,路堑内雪量堆积越多,路堑内积雪平台也会越快到达雪量承载上限。

In order to study the distribution characteristics of wind and snow inside and outside the roadbed under the action of snow-drifting in railway cutting area, as well as to reduce the deposited snow amount in railway cutting, a wind tunnel test using native snow in snow-drifting disaster-prone area based on the newly-built railway cutting and three different forms of snow fences was carried out. Combined with the CFD multiphase flow model analysis method, the same model as the wind tunnel test was established to obtain the flow field distribution in different areas inside and outside the railway cutting. The test results were compared with the winter snow distribution in the actual snow fence area. The results show that the snow distribution in the simulated test is consistent with that in the field test section. The existence of snow platform in the cutting can make more snow particles deposited in the snow platform, increase the wind speed on the subgrade surface, and reduce the snow amount deposited on the top of the subgrade under the action of snow-drifting. The snow fence mainly affects the flow field distribution outside the cutting, and the snow particles are deposited on both sides of the fence and inhibit the erosion effect on the top of the cutting slope;the distance between the snow fence and the cutting should be more than ten times the height of the fence. The influence of the snow fence on the flow field is nonlinear with the height of the fence;the effect of each row of snow fences on the flow field is basically the same when multiple rows of fences are used. Increasing the wind speed will reduce the natural snow depth in the balance state of snow-drifting, so that more snow particles outside the cutting are blown into the cutting. The cutting structure can significantly weaken the flow velocity, and the snow particles near the ground in the cutting are still in a state less than the starting speed under the condition of the six levels wind. The higher the wind speed of incoming flow, the more snow accumulation in the cutting, and the faster the snow platform in the cutting will reach the upper limit of snow capacity.