| The Mu Us sandy land has a harsh environment and the gale lasts longer.The sand dune shrubs grown in the local area were eroded by wind and sand,and the internal structure of the sand dune shrubs was damaged,resulting in the decline of the sand dune shrubs and the decline of the sand willow shrubs Will cause similar natural phenomena such as weather in Yangsha.Aiming at a series of ecological problems caused by the decline of the sand dune shrubs,the sand dune shrub sand dune model was used to simulate the wind and sand in the wind tunnel,and the wind sand environmental variable similarity theory(SEMS)The time conversion between the wind tunnel simulation test and the field test is to reveal the wind erosion resistance of the Salix shrub sand pile and predict the durability of the shrub sand pile.The research results are as follows:(1)Under the net wind simulation test,the wind speed changes around the sand dune sand pile and the surface roughness calculation results of the sand pile are consistent with the field test results.The changes of wind speed at the height of 50cm and 200cm in the sand dune field in the wild are basically the same as those at the corresponding heights of 3.3cm and 13.3cm in the sand aune model,and the wind speed is on the leeward surface of Sanx shrub H(The height of single Salix plant)was the lowest,and the wind speed decreased the most at this point,indicating that the shrubs at the leeward surface H had the strongest wind blocking ability.The roughness of the surface of the sand piles in the wild and in the wind tunnel at the locations of the wilderness and simulated wilderness,the windward surface-H point,and the leeward surface at the 0.5H,H,7H measurement points,the probability P values are 0.713(P?0.05)),0.067(P?0.05),0.970(P?0.05),0.397(P?0.05),0.407(P?0.05),the difference in surface roughness between the field and the wind tunnel is not significant,the sand willow shrub sand pile model able to carry out simulation test well.(2)At wind speeds of 6m/s,9m/s,and 12m/s under the net wind simulation test,the sand transport rate around the shrub sand pile model showed a downward trend with increasing height,and the sand transport rate was mainly distributed in the sand collector at the height of 0?12cm,the maximum sand transport rate occurs at the height of 0?2cm;The sand wind test has three wind speeds of 6m/s,9m/s and 12m/s,the sand transport rate height is mainly distributed in 2?24cm when the sand flow is 30g/min,45g/min and 60g/min,and the height distribution range is wider,and the impact of the sand blowing wind on the shrub sand pile is greater.When the wind speed is 6m/s and 9m/s,the difference between the sand transport rate and the net wind is not significant,and the wind speed and the sand flow are not enough to cause a significant change in the sand transport rate;when the wind speed is 12m/s,the sand transport rate There is a significant difference between the wind transport rate and the net wind transport rate.The critical wind speed at which the transport rate changes is 9m/s.(3)Under the wind speeds of 6m/s,9m/s and 12m/s,the mass loss rate of shrub sand piles increases with increasing wind speed.The mass loss rates of the three sand piles at 6m/s wind speed were respectively were 1.49%,1.71%,1.32%;the mass loss rates of the three sand piles at 9m/s wind speed were 4%,4.02%,3.24%;the mass loss rates of the sand piles at 12m/s wind speed were the largest,at 8.30%,8.86%,7.07%respectively.In the sand-blown wind simulation test at 30g/min,45g/min,60g/min sand flow,the mass loss rate of each shrub sand pile showed an overall upward trend with the increase of wind speed and sand flow.At 6m/s wind speed,the wind speed is low,and the sand flow is the main factor affecting the mass loss rate of each sand pile.At 9m/s and 12m/s wind speeds,the mass loss rate may be affected by the shape parameters of the sand piles,so that the mass loss rates of different sand piles under the corresponding sand flow rates vary greatly.At the same wind speed.the mass loss rate of sand piles(1,2,3)is significantly different under different sand flow rates,and the sand flow rate has a greater impact on the mass loss rate of the sand piles.(4)Using SEMS to obtain the proportional relationship between the actual erosion time in the field and the wind tunnel erosion time,for the field the erosion time of shrubs under the actual dust environment was estimated.When the sand flow is 30g/min and 60g/min,it is estimated that the actual erosion time at each wind speed is the least at 30g/min and the longest at 60g/min.When the wind tunnel test is 5min and the sand flow is 30g/min and 60g/min,it is estimated that the actual blow time under the three wind speeds is the least when the sand flow is 30g/min,and the blow time is 1.76×104d,1.18×104d,8.81 × 103d.The blow-off time under the sand flow rate of 60g/min was the longest,which were 3.53 × 104d,2.35 × 104d,and 1.76 × 104d,respectively. |
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