Comparison of Wind Prevention and Sand Blocking Effects of 4 Types of Sand Blocking Nylon Nets in the Central Taklimakan Desert

Sand blocking nylon nets are commonly knitted with uniform porosity,however,vertical sand flux was unevenly distributed. In this study,three types of sand blocking nylon nets with different structure were designed, i. e.,the wide tripped net with sparse upper-porosity and dense lower-porosity( A),wide tripped net with dense upper-porosity and sparse lower-porosity( B),and narrow tripped net with alternative dense and sparse porosity( C). They were settled on the inter-dune sand lowland in the hinterland of the Taklimakan Desert,and the net with uniform porosity was taken as the contrast( CK). The wind speed at different heights from ground surface and the deflation depth and deposition height on the ground around the nets were surveyed. The collected data were analyzed to understand the wind prevention and sand control effect of the nets. The results are as follows: ① The effective wind prevention range of the three types of nets( A,C and CK) was about 15H,but that of net B was about 6H only. The wind speed reduction rates at 3 heights( 0. 15 m,0. 3 m and 0. 5 m) from 10H range were significantly different,and they were in an order of C A B CK; ② The difference of deposited sand mass of the three types of nets( A,C and CK) was not so significant,but the deposited sand mass of net type B was lower than that of other three types of nets: ③ In conclusion,the wind prevention and sand control effect of net type C was the highest,that of net type B was the lowest,and there was no significant difference between net type A and CK. These results could provide a new idea for the optimal design of the structure of high sand barriers,and give some scientific basis for sand control engineering construction.