Numerical Analysis Of Eroding Mechanism Of Wind-Sand Flow On Railway Embankment

In desert,Gobi and sandy areas,railway undoubtedly plays an important role in the transportation.However,the constraints of the natural environment,the construction and maintenance of railway embankment is facing a serious crisis.By the Wind-sand flow erosion,it causes railway lines are hard to run properly.In accordance with different regions which eroded by wind erosion and sand burial,a large number of domestic and foreign experts have conducted rational analysis and feasible studies.They proposed many effective prevention measures and governance approaches.It can be said to have made relatively good results.Studies to wind-sand flow and sand accumulation process and sand motion trajectory around railway embankment are still exist deficiencies.It is necessary to do further research for the wind-sand flow field around the railways.In this paper,FLUENT software is used to do aerodynamic simulation and analyze the characteristics of the wind-sand flow field surrounding railway embankment.On base of three-dimensional unsteady Euler two-fluid and steady Lagrange discrete phase model,I comprehensively analyzed characteristics of sand accumulation process and motion trajectory,to optimize the height of wind-break wall.This is to ensure the smooth flow of railway lines and security operations has important practical significance.The results show that wind-sand flow along the model of outlet orientation,the wind-sand flow velocity around embankment increases gradually,swirls in the leeward slope and whirlpool area is gradually increasing.Wind-sand flow generates the maximum wind speed on the windward side of 0.3m at the shoulder,which is closest to the model outlet,comprising with the initial wind speed increased by 25%,indicating where the most powerful embankment erosion.At windward slope and leeward slope,air phase facilitate to sand phase movement.On the embankment top surface,air phase impede the movement of sand phase.At both windward and leeward side of embankment,sand was gradually accumulated and then gradually turned wind erosion.Then on the foot of windward slope,embankment top surface and the foot of leeward slope sand is always been cumulated.Oblique wind changes its direction,that is the velocity of velocity inlet 1 changed from 1m/s to 3m/s,so that sand volume fraction on embankment top surface increases about 12%,the largest sand accumulation area on embankment top surface moves rearward and it makes the process that fall to the foot of slope slow down.Oblique wind speed changes,that is velocity inlet 2's air friction velocity changes from 0.66m/s to 0.99m/s and sand friction velocity is from0.15m/s to0.33m/s.so that the maximum sand volume fraction on embankment top surface increases by about 34%.sand accumulation area on embankment top surface becomes large and sand is easy to accumulate on the foot of windward slope,causing the railway embankment damage for erosion.In the flow field inside,the number of sand grains at railway embankment 's windward slope is more than the number at leeward slope.The number of sand grains is the least on the top surface.The farther away from velocity inlet 1,the less drops on windward slope,top surface and leeward slope.With the sand particle size's increase and friction velocity's decrease,the number of sand grains which drops in the windward and leeward slopes gradually increased,and almost does not change on the top surface.When the height of the retaining sand wall at 2m,it can effectively reduce the speed of the flow field around the embankment,lessen the degree of sand accumulation,and causes already deposited sand around embankment continue raising and moving.