Study on the Aeolian Sand Control Effect of SandMoisture
| Autor: | Yi-Heng Tsai, 蔡易衡 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 This study was planned to investigate the aeolian sand control effect of sand moisture. 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, as well as the restraint duration on sand movement of sand moisture. 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 In addition, the sand field capacity of Da-an river sample was about 2.98%. The field capacity was used as a standard moisture value to spray the sand to control sand movement. The aeolin sand control effect and restraint duration of sand movement decreased as the wind velocity increased. The aeolian sand amount started to increase significantly when the blown duration was 180-190 minute at a wind velocit of 10m/s. The timing to re-spray sand to restore the sand moisture was based on the duration. Study estimated the costs to restore the sand moisture to field capacity at a soil depth of 3 cm with different wind velocity were respectively as follow: NT 4552 dollar/ha-day at a speed of 15 m/s, NT 3895 dollar/ha-day at a speed of 14 m/s, NT 3442 dollar/ha-day at a speed of 13 m/s, NT 2997 dollar/ha-day at a speed of 12 m/s, NT 2116 dollar/ha-day at a speed of 11 m/s, NT 1677 dollar/ha-day at a speed of 10 m/s, NT 1465 dollar/ha-day at a speed of 9 m/s, NT 1252 dollar/ha-day at a speed of 8 m/s. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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