筛分时间和投加量对沙漠沙干筛分析结果有着直接的影响，但目前对此鲜有报导。本文研究筛分时间（1~17 min）和投加量（20~100 g）对沙漠细沙筛分效果的影响。结果表明：在干筛分析过程中，20 g投加量时筛分效果在3 min达到稳定，而投加量在30~100 g时约在9 min达到稳定，意味着沙漠样品筛分需要的最短筛分时间与样品投加量有关。光学显微镜检测表明，干筛筛分的沙粒样品仍有11%~30%粗颗粒和1%~4%的细颗粒存在，此混杂比例具体因沙粒粒级而异。颗粒形状等因素造成了干筛筛分法与光学显微镜分析法的差异。
It is doubtless that sieving duration and sample weight can affect dry sieve analysis. However, the effect seldom had been reported. This paper is to understand the effect under different sifting duration (1-17 min) and weight (20-100 g). It indicates that the minimal sieving duration to separate effectively from different size particles is 3 minutes for 20 g samples and 9 minutes for 30-100 g samples. Uniform sand particles sieved dryly has 1%-4% of finer particles and 11%-30% of coarser particles in terms of microscopy method, indicating result of sieving method are less than that of microscopy method due to irregular shape of sand particles.
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