| High-efficiency sand barriers have been widely used in the prevention and control of wind and sand in line engineering.With the deepening of engineering sand control research,double-row and even multi-row high vertical sand barrier systems have gradually been accepted by people.The needs of both use simplifications and assumptions.For the researchers,the conclusions or conclusions of different conclusions are different.The author has carried out wind speeds on four different heights of sand barriers such as Ulanbu and desert sand-sand roads.The flow field observation,surface particle size characteristics and sediment transport volume were measured,and the Fluent numerical method was used to simulate and supplement the wind-blown flow characteristics of double-row high vertical sand barrier under different working conditions.The results show that:(1)In the low-speed(<12m·s-1)flat quicksand environment,the four types of height(60cm,80cm,100cm,120cm)double-row flow field are mainly "double-peak type",and the flow field changes mainly by "The lift-acceleration-deceleration-stationary-lift-down-recovery" form exists,and the range of the wind speed in the transition zone between the two peaks is gradually increased by 3 to 4 m,5 to 6 m,6 to 7 m,and 8 to 10 m,respectively.The minimum wind speed acceleration rate after the second row of sand screens is smaller than the wind speed rate after the first row of sand screens,that is,there is a superposition effect of reducing wind speed between the two rows.(2)From the analysis of sediment transport from 0 to 50cm,the power function relationship between near-surface wind speed and sediment transport is Q=0.00004V5.9337,and the sediment transport amount of each row of intermediate transition zone is 4 In the range of-8m,there is a tendency to rise first and then rise.The change of surface particle size parameters around the sand barrier is mainly composed of Zhong sha and fine sand,and the fine sand accounts for about 80%,the average particle size is 1.9(p-2.3(p,and the sorting coefficient is between 0.40 and 0.52.Fluctuation,the skewness is between 0 and 0.05,and the peak state is between 0.945 and 0.960.(3)From the perspective of numerical simulation of wind-blown sand flow,the flow field of double-row high vertical sand barrier under different working conditions is mainly in the form of "lift-deceleration-recovery",and the vertical wind speed profile of the transition zone of double-row sand barrier gradually Approaching the "S" form,the better the protective effect of the sand barrier,the more "S" form,the horizontal flow field mainly exists in the form of "V" and "W".As the number of barriers increases,the amount of sediment increases gradually;as the height increases,the amount of sediment increases and the position of sand accumulates in the second row;with the increase of wind speed in extreme weather,double row height Vertical sand barriers gradually lose their protective effect.(4)Based on the results of field observations and numerical simulations,the reasonable spacing of the four types of high-rise double-row high vertical sand barriers is 4m,5.5m,6.5m and 8m respectively.The recommended number of laying belts can be adjusted according to the actual wind conditions and linear sand damage:60cm and below 3 to 4 belts,80 to 100cm high 2 to 3 belts,120cm high and 1 to 2 belts.In actual laying,the recommended laying height is between 1.0 and 1.5m.It is not recommended to increase the height of the sand barrier.It is to adopt the principle of "horizontal multi-channel laying" as much as possible to achieve the effect of decreasing wind speed and sediment transport,and to maximize the protection benefits of sand barriers. |
PDF Full Text Request