关键词: 防雪棚洞, 风洞模拟实验, 公路风吹雪, 模拟介质

Abstract:

There is a severe phenomenon of blowing snow by wind in winter in Mayitas area of Xinjiang. Road traffic interruptions and casualties caused by wind and snow disasters often occur. The existing engineering measures can alleviate the problems of low visibility and problems with accumulating snow on pavement caused by wind and snow to a certain extent， but cannot completely eliminate the impact. Aiming at the problem that the blowing snow disaster difficult to be completely cured under strong wind conditions， a shed tunnel engineering treatment scheme is proposed， and a wind tunnel simulation experiment is carried out on the shed tunnel form and snow prevention scheme at the entrance of the tunnel. The wind tunnel experimental section is 8 m long， 1.3 m horizontally wide and 1 m high. The shed tunnel model is made by 1：60 scale 3D printing method， the snow barrier model is made of wooden strips， and the simulation medium is made of fine sand， refined salt and sawdust. Firstly， three kinds of shed structures， including fully enclosed， overhanging and ventilated， were simulated under the condition of 90° wind direction， and compared with the form of blowing snow stacking. Three parameters for similarity were used： density， particle size and stacking shape. The similarity is determined by weighted Euclidean distance between simulation medium and blowing snow， the similarity of the slump angle of the predecessors is verified， and the most suitable medium for simulating blowing snow is deduced. According to the experimental results， combined with the actual situation of wind blowing and snow disasters in Mayitas， flow field of the closed shed tunnel by a wind direction angle of 30° has been separately conducted with or without protective measures. The results show that when the wind tunnel stacking experiment is used to study the deposition state of blowing snow under non-low temperature conditions， the sawdust has good similarity with the blowing snow in the process of wind and snow movement. A large amount of medium was poured into the ventilated shed during the experiment， which proved that its anti-wind and snow performance was not ideal. By contrast， the closed shed and the overhanging shed have better wind and snow prevention effects. The snow barrier has a good blowing snow inhibition function at the entrance. From the stacking experiment， in the comparison with and without snow barrier， volume of the medium in the shed is very different， which proves that the snow barrier can effectively prevent the blowing snow from entering the shed. Among them， the difference in wind speed inside and outside the shed is obvious， which proves that snow barrier can significantly reduce the wind speed outside the shed and has the function of inhibiting the formation of weak wind areas inside the shed. The study has confirmed that the shed tunnel project with suitable snow barrier layout plan for tunnel entrance protection is an effective means to control wind and snow disasters. For highway traffic in Xinjiang， it is a feasible solution to use shed tunnel engineering to control blowing snow disasters. After dealing with the snow deposition at the entrance of shed tunnel， the shed tunnel engineering form of low-cost environment integration and the vehicle operation safety guarantee measures of long-distance shed tunnel are the problems that need to be solved in the future.

Key words: snow-defence tunnel, wind tunnel simulation experiment, blowing snow on highways, simulation medium