Numerical simulation of flow field structure and sand accumulation around railway subgrade

Abstract

Based on the current situation of railway sand damage in Tuotuohe region, the structure of wind-sand flow and the spatial distribution characteristics of sand particles on both sides of railway embankment are simulated by CFD Fluent software according to flow field measurement and wind tunnel test.The results demonstrate that the subgrade's shoulders are vulnerable to suffering from wind erosion; The sand particles' spatial deposition location and thickness are significantly affected by the incoming wind velocity and the railway subgrade. When the low incoming sand-carrying wind velocity, a lot of sand grains fall and are deposited at the railway embankment slope foot due to the sand-carrying wind velocity reduced. Meanwhile, the amount of leeward side deposited sand particles exceeds the windward side due to the vortex action to the subgrade leeward side region. As incoming sand-carrying wind velocity increases, eddy current development intensity at the leeward foot of the subgrade increases, which further results in a large number of sand particles accumulated and deposited at a certain distance away from the railway embankment slope foot; Sand particle deposition location on the railway embankment top surface mainly occurred closing to the leeward side's subgrade shoulder. The phenomenon of sand deposition is more serious in the condition of weak wind and multiple wind directions; Different ground surfaces affect the density of windy sand flow structure, indirectly affecting sand particle deposition thickness on both sides of the railway embankment.

Keywords: Tuotuohe region; flow field; numerical simulation; railway subgrade; sand particle accumulation.