基於暴露角分佈隨機性的非均勻礫石起動研究

基於床面非均勻泥沙及其位置分佈的隨機性，試驗設計和觀測了五種不同級配的非均勻礫石暴露角，並對其分佈規律進行了統計分析。結果表明，各粒徑級泥沙暴露角機率分佈均服從常態分佈；較中值粒徑細的泥沙暴露角均值大於中值粒徑泥沙暴露角均值，較中值粒徑粗的泥沙暴露角均值小於中值粒徑泥沙暴露角均值。細顆粒占比越多，暴露角均值越小；粗顆粒占比越多，其均值越大。床沙級配越寬，細顆粒暴露角均值越大，粗顆粒則越小。在此基礎上，結合水流的隨機特性，推導出非均勻沙起動全機率公式，並將其代入輸沙率模型中進行驗證，結果符合較好。

關鍵字

非均勻沙；暴露角；隨機性；機率分佈

並列摘要

Based on the randomness of the non-uniform sediment on the bed surface and its location distribution, the experiment designed and observed five different gradation of non-uniform gravel exposure angles, and carried out a statistical analysis of their distribution rules. The results show that the distribution law of the exposure angle of the gravel of each particle size class is basically the same, and all obey the normal distribution; the distribution law of the exposure angle of the sand close to the median size is basically the same as that of the uniform gravel of the same particle size, and the average exposure angle is basically the same; the average exposure angle of gravel with a finer particle size is greater than the average exposure angle of gravel with a median particle size, and the average exposure angle of gravel with a coarser particle size is less than the average exposure angle of sand with a median particle size; the average exposure angle of fine particles decreases as the proportion of fine particles increases, and the average exposure angle of coarse particles increases as the proportion of coarse particles increases; the wider the bed sand gradation, the greater the average exposure angle of fine particles , The coarser particles are smaller. On this basis, combined with the random characteristics of water flow, the full probability formula for the initiation of non-uniform sand is derived, and it is substituted into the sediment transport rate model for verification. The results are in good agreement.