# Experimental Research on Sand Sediment Protection on Railway Tracks
## 4 Experiment on Sand Deposition on the Tracks
### Results and Discussion  
The experiment results are shown in Table 2. It can be seen that during the 8 min sand deposition period, the height of deposited sand in front of the tracks under experiment are slightly different. This may be explained by the different dust emission amounts in the  
Figure 7: Schemes of Field Experiment Based on Simple Wind Tunnel. (**a**) simple experimental wind tunnel; (**b**) arrangement of the experimental devices; (**c**) general view of the experimental setup; (**d**) measurement of sediment height. experiment. Nevertheless, the ratio between the heights of deposited sand on the front (first) and rear (second) tracks is relatively stable. Therefore, the ratio between the heights of deposited sand on the front and rear tracks was used to characterize the sand prevention effect of the baffles, defined as \"sedimentation height ratio\". Additionally, unless otherwise specified, the heights of the square timbers or inclined baffles placed on the tracks should be the same as the height of tracks, and both heights should be calibrated with a level gauge. According to relevant railway standards, on railway tracks, safety distance is defined as a distance not greater than 25 mm above the tracks. Thus, in the experiment, the height ratio of deposited sand between the front and rear tracks was measured when the baffles were installed 20 mm higher than the track. The results of relevant data are listed in Table 2. From the table, the ratios between the heights of deposited sand are 0.43 and 0.40, with the mean value of 0.415 in the case of the original track, and 0.30 and 0.33, with the mean value of 0.315 when installing a square timber with a width of 115 mm the same height as the track. The height of sand deposited decreases by about 24.1%, which shows that installing a square timber the same height as the track can effectively reduce the sand deposited on the rear track. However, square timbers helped curb the sand deposition on rear track, but sand deposited heavily in front of the square timbers. This indicates that square timbers can improve the sand deposition on the rear track, but aggravate the sand deposition in the front part of the tracks. Then, baffles with different inclination angles were placed in the track. First, a 45\({}^{\circ}\) inclined baffle, with a length of 100 mm on two right angled sides and 141 mm on hypotenuse side, and the same height as the track, was placed on the track, which produced a sand deposition ratio of 0.32. Obviously, this result is almost the same as that produced by the square timber approach, indicating that the two approaches have basically the same effect on the sand deposition velocity on the rear track, except that inclined baffle would result in less sand deposition in the front as compared with square timber, so the inclined baffle outperforms the square timber in terms of sand prevention effects. Since a train can travel safely over objects placed within 25 mm above the track, the height of the inclined baffle can be increased as a whole. For the sake of safety, the device was lifted 20 mm and the experiment was repeated. It was found that after the placement of the 45\({}^{\circ}\) inclined baffle, the sedimentation height ratio between the front and rear tracks was 0.23 and 0.25, with the mean value of 0.24. Compared with the original track, the sand deposition on the rear track decreased by 42.2%, which is comparable to the results present by [PERSON] et al. [31] on the sand prevention efficiency of desert railways. However, the method proposed in this paper has lower construction cost. The field experiment was accidentally interrupted due to the need of COVID-19 epidemic control, so a simulation experiment was conducted in the laboratory to supplement the changes of sand deposition on the front and rear tracks when various baffles with different inclined angles and heights were placed in the tracks. See Figure 8 for the experimental setup and Table 3 for the experimental results.