The Compound Change Regulation Of Windbreak And Sand-fixing Effect Of Nylon Grid Sand Barrier

The layout parameters of grid sand barrier directly affect the compound effect of windbreak and sand-fixing effect.Quantitative expression of its complex law is of great significance to the determination of sand barrier configuration mode.Nine kinds of nylon grid sand barriers with different heights(30cm,20cm,15cm)and sizes(1m × 1m,1.5m X 1.5m,2m X 2m)were laid at the artificially leveled wind-blown sand observation site in Ulanbuh Desert.The horizontal spatial variations of wind speed,structure of wind-sand flow and grain size of surface sediment in sand barrier were measured,and the composite variation law of windbreak and sand-fixing effect of nylon grid sand barrier was comprehensively analyzed.The results show that:(1)The wind speed in different sizes of nylon grid sand barrier is greatly affected by the height of the sand barrier,followed by the size of the sand barrier,but all show a sharp decrease in the front(0-12m),a slow decrease in the middle(12-24m),and a stable change in the rear(24-36m).three sizes of sand barriers of 1m × 1 m,1.5m X 1.5m and 2m X 2m reduce wind speed by more than 50%after entering the barrier 9.5m,13.6m and 13.6m,respectively;three kinds of heights sand barriers of 30cm,20cm and 15cm reduce wind speed by more than 50%respectively in 6.5m,13.6m and 13.6m.(2)The sediment transport in the nylon grid barrier decreases gradually with the increase of horizontal protection distance,and the leading edge of the barrier changes most significantly.Within the range of 0-13.6m for three sizes of sand barriers of 1m X 1m,1.5m X 1.5m and 2m X 2m,the sediment transport amount is 82.68%,77.79%and 76.62%of the total sediment transport amount.Within the range of 0-13.6m for three kinds of heights sand barriers of 30cm,20cm and 15cm,the sediment transport amount is 88.82%,76.02%and 72.26%of the total sediment transport amount.(3)The wind speed and sediment transport rate of the nylon grid sand barrier with different specifications decrease in the form of logarithmic function with the increase of the protection width,and this composite change is most affected by the height of the sand barrier,followed by the size of the sand barrier,and not significantly changed with the indicated wind speed.The comprehensive cost of sand barrier laying and the comprehensive benefit of nylon grid sand barrier with a height of 30cm and a size of 2m×2m are the best.It is recommended to be used in the sand control project of Ulanbuh desert.