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|標題:||A Study on the relation between sand movement and moisture content
|關鍵字:||砂粒含水率;飛砂;風洞;soil moisture content;aeolian sand;wind tunnel||Project:||水土保持學報, Volume 47, Issue 1, Page(s) 1259-1272.||摘要:||
This study was planned to investigate the relations between sand movement and moisture content in the sand. The estuary of Da-an river, an area full of severe hazards of aeolian sand and fugitive dust, was chosen as the study site. A soil experiment was conducted in laboratory to determine the physical properties of the sand sample collected from the site. Besides, a wind tunnel experiment was carried out to measure the starting threshold of wind velocity and the moisture content of the sand. According to the soil experiment results of the physical properties of the sand, the soil texture of Da-an river was sorted as poorly graded sandy soil, the moisture content of natural dried sand was about 0.5%, the average particle size was about 0.313mm, the density of sand was 2.72 g/cm³, and the shape coefficient of sand was 0.9794.
As to the wind tunnel experiment, the results showed that when moisture content of sand was 0.13%, the starting threshold of wind velocity of the sand particles decreased with different diameters were respectively as follows: 13-14m/s for the sand with 2-0.84mm, 7-8m/s for the sand with 0.84-0.42mm, 6-7m/s for the sand with 0.42-0.25mm, 4-5m/s for the sand with 0.25-0.15mm, and less than 4m/s for the sand smaller than 0.15mm. According to the other results, the starting threshold of moisture content for the sand particles increased with different diameters at different starting wind velocities were respectively as follows: 0.475% for the sand with 2-0.84mm at a speed of 14m/s, 0.730% for the sand with 0.84-0.42mm at a speed of 8m/s, 2.045% for the sand with 0.42-0.25mm at a speed of 7m/s, 2.115% for the sand with 0.25-0.15mm at a speed of 5m/s, and 2.255% for the sand smaller than 0.15mm at a speed of 4m/s
本研究為瞭解砂粒運移特性與含水率之關係，選定大安溪鄰近出海口處，飛砂及揚塵危害嚴重地點，採集現地砂粒樣本後，攜回實驗室進行砂粒物性分析，並於風洞從事砂粒起動風速與含水率之觀測；物性分析結果顯示，大安溪土壤質地為級配不良的砂土，自然風乾時含水率約為 0.5%，平均粒徑為 0.313mm，密度為 2.72g/cm³，形狀係數為 0.9794。
在風洞試驗方面，當含水率為 0.13％ 時，砂粒之起動風速隨粒徑遞減而遞降，粒徑在 2～0.84mm、0.84～0.42mm、0.42～0.25mm、0.25～0.15mm 及 0.15mm 以下之砂粒，其起動風速分別為 13～14m/s、7～8m/s、6～7m/s、4～5m/s 及 4m/s 以下；又當各粒徑之砂粒在起動風速分別為 14m/s、8m/s、7m/s、5m/s 及 4m/s 時，砂粒之起動含水率隨粒徑遞減而遞增，粒徑在 2～0.84mm、0.84～0.42mm、0.42～0.25mm、0.25～0.15mm 及 0.15mm 以下之砂粒，其起動含水率分別約為 0.475% 、0.730%、2.045%、2.115% 及 2.255%。
|Appears in Collections:||第47卷 第01期|
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