Numerical Analysis On Distribution Characteristics And Variation Of Line Sediment Accumulation In Sand-blown Area

Desert is widely distributed in northwest China.The influence of sand flow on desert railway operation safety cannot be ignored.Wind sand erosion of railway subgrade,sand cover the line,resulting in train operation blocked,greatly reduced traffic safety.Our country always pays great attention to the construction,research and management of desert railway.Railway departments,universities and scientific research institutes have done a lot of research work on this,and obtained a large number of important results.At home and abroad for railway across the sand in the study area are mainly concentrated in the subgrade wind erosion characteristics and the effect of the wind resistance of sand facilities,also have relevant personnel research as the movement mechanism of sand and wind flow field around a frantic jumble orbit characteristics,but ignores the subgrade and track of sand flow and line combination of sand surface.Based on the computational method of fluid mechanics and numerical simulation,the combined analysis model of aeolian sand flow passing through "track + subgrade" is established in this paper to study the variation of sand accumulation distribution along the line.The main contents are as follows :(1)According to euler two-fluid model principle,a flat fluidized bed model with sand particles laid at the bottom of the model is established,and the numerical simulation results are compared with the measured results of existing lines to clarify the distribution law of railway aeolian sand flow field.(2)Study the sand accumulation process of embankment and road cut under the condition of orthogonal wind direction and line direction.(3)Study the distribution characteristics of sediment around railway track under orthogonal wind direction and the variation rules of sediment on both sides of railway track with wind speed,surface roughness,embankment height and cutting depth.(4)The sand accumulation distribution characteristics at different positions of the line under oblique wind direction were simulated and compared with the simulation results of the influence of forward wind to summarize the influence of wind direction on the sand accumulation distribution of the line.The main conclusions are as follows :(1)When the wind direction is orthogonal to the direction of embankment line,the higher the wind velocity is,the higher the height of sand accumulation on both sides of the track is;With the increase of embankment height,the height of sand accumulation on windward side of rail decreases,while that on leeward side of rail increases.The larger the surface roughness,the smaller the total amount of sediment deposited on both sides of the track.(2)When the wind direction is orthogonal to the direction of cutting line,the sand amount of line surface area decreases with the increase of wind speed;The deeper the cutting,the more sand accumulated on the windward side of the track,and the less sand accumulated on the leeward side;The larger the surface roughness is,the coverage area of sand between rails decreases.(3)When wind direction and line strike cross diagonally,the height of sand deposited in the leeward part of the track is greater than that in the windward part.The smaller the wind direction Angle is,the larger the sand velocity is,the larger the maximum height of sand accumulated on the windward side of the track is,and the more easily the track is buried by sand accumulated.(4)Based on the influence of various factors on the line sediment deposition,the order of influence degree is wind direction Angle & GT;Cutting depth >Embankment height >Wind sand velocity& GT;Surface roughness.