Numerical simulation of sand transfer in wind storm using the Eulerian-Lagrangian two-phase flow model

Wind Dynamic Characteristics and Wind Tunnel Simulation of Subgrade Sand Hazard in the Shannan Wide Valley of the Sichuan–Tibet Railway

The Shannan wide valley section of the Sichuan–Tibet Railway is located in the middle reaches of the Yarlung Zangbo River, where sand hazard is severe. A wind tunnel simulation experiment was conducted by establishing a subgrade model and performing field observation to carry out research on the dynamic environment of blown sand and the sand hazard formation mechanism of subgrade in the Shannan wide valley. Observation results showed that the sand-moving wind of the Shannan wide valley was chiefly derived from the ENE direction, and the resultant sand transport direction was WSW. Wind speed, the frequency of sand-moving wind, the sand drift potential, and the maximum possible sand transport quantity were relatively high in the spring. Meanwhile, the dynamic of the wind-blown sand flow was further enhanced in the spring, particularly influenced by the flow action of the Yarlung Zangbo River. Thus, sand hazard mainly occurred in the spring. The Sichuan–Tibet Railway subgrade evidently changed the wind speed, the wind-blown sand flow field, and conditions of transport and accumulation. Within the distance of 5 times the model height in the windward direction and at the subgrade top center to 20 times the model height of the leeward direction was the wind speed deceleration zone, resulting in sand particle sediments. A wind speed acceleration zone appeared on the subgrade windward slope shoulder, resulting in wind-blown sand flow erosion. This study provides a scientific basis for sand hazard prevention and control in the Sichuan–Tibet Railway.

Comparing performances of a triangular embankment and a rigid wall-type barrier in sandstorms using simulation and a wind tunnel test

The movement of sand particles and their accumulation on railway tracks are among the major problems observed in desert areas, which may impose huge maintenance and repair costs. One solution is to create a protective barrier in the vicinity of railway tracks to reduce sand deposition on these tracks. The present study introduced a triangular embankment due to its construction simplicity and low cost and compared it with a rigid wall-type barrier. At first, both models were compared in terms of the streamline and the sand mass flux with a two-phase flow of sandstorm numerical calculations. Then, the sand mass flux was measured for the rigid wall-type barrier using an experimental wind tunnel test. Moreover, the effects of wind speed, wall height, the zero-porosity barrier on the mass flux profile, and the deposition reduction of sand particles were examined after the barrier placement. Finally, the triangular embankment behavior was studied in a wind tunnel. The results revealed that the triangular embankment could increase the safe area after the barrier placement by up to 25%. Further, the triangular embankment was proven to be a permanent and cost-effective solution for protecting railway tracks in windblown sand-prone areas.