吳富春2006-07-252018-06-292006-07-252018-06-292004http://ntur.lib.ntu.edu.tw//handle/246246/10765本研究探討非均勻砂礫之分區可動性 與啟動機率。研究結果顯示分區可動性與 無因次有效剪應力之關係可以累積對數常 態分布表示，其均值與標準偏差在含砂量 ＜0.34 時均隨含砂量線性遞減。研究結果 亦顯示在無因次剪應力＜0.25 時，啟動機 率隨亂流強度而遞增；然而在無因次剪應 力＞0.25 時，啟動機率則隨亂流強度增大 而遞減；無因次剪應力＝0.25 時，不同亂 流強度所對應之啟動機率一致均為0.3。We investigate the fractional mobility and entrainment probability of nonuniform sand/gravel sediment. The results reveal that the relation between fractional mobility and dimensionless effective shear stress is well approximated by the cumulative lognormal distribution, with its mean and standard deviation linearly decreasing with sand content for the range < 0.34. The results also reveal that for smaller values of dimensionless shear stress (< 0.25), the entrainment probability increases with the turbulence intensity, whereas for larger values of dimensionless shear stress (> 0.25), the entrainment probability decreases with the increase of turbulence intensity. For dimensionless shear stress = 0.25, the entrainment probabilities corresponding to different turbulence intensities consistently remain at 0.3.application/pdf115863 bytesapplication/pdfzh-TW國立臺灣大學生物環境系統工程學系暨研究所非均勻砂礫分區可動性啟動機率含砂量亂流強度Nonuniform sand/gravel sedimentfractional mobilityentrainment probabilitysand contentturbulence intensityreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/10765/1/922211E002089.pdf