海洋地质与第四纪地质2009，Vol.29Issue(5)：145-152,8.DOI:10.3724/SP.J.1140.2009.05145
激光粒度仪分析结果中假峰形成的原因及消除方法
WHAT CAUSES THE FAKE KURTOSIS AND HOW TOAVOID IT IN GRAIN-SIZE MEASUREMENT
摘要
Abstract
A false mode >100 μm often occurs in laser grain-size measurement. The causes of the false mode may be that the water amount <800 mL leads to a high liquid viscosity and in turn stirs more bubbles. Another cause may be that larger quantity of a sample may induce a larger shading level of light (＞13%) and a higher liquid viscosity in turn may release bubbles with difficulty. An inappropriate pump speed or an ultrasonic dispersion time shorter than 2. 5 min also may result in false modes appearing. Several principles to avoid false modes are concluded. The shading level of light (obstruct light) should be 8%～13%. The amount of samples is determined according to their types. The appropriate quantity is～0. 1 g for clay samples, 0. 2 g for loess and fine silty sand samples, 0. 4 g for coarse silty sand samples, 0. 6 g for fine sand samples and 1. 0 g for sand samples in order to keep the light shading level of 8%-12%. The water amount of ～1 000 mL and the ultrasonic dispersion time of >2. 5 min before measuring are necessary to eliminate false modes of grain size distribution. For clay or fine silty sand (median size<10 μm), false modes may occur even though water amount is more than 1 000 mL. In the case, false modes can be identified and eliminated by changing stir speed. The mode whose median size is >100 μm and does not occur in all conditions may be a false mode. The false mode may disappear when the stir speed is reduced to 2 000 for a sample with lower light shading level. The false mode may disappear when the stir speed is increased to 3 200 for a sample with higher light shading level.关键词
粒度分布/假峰/激光粒度测量Key words
grain-size distribution/false mode/laser grain-size measurement分类
天文与地球科学引用本文复制引用
贾红娟,秦小光,刘嘉麒..激光粒度仪分析结果中假峰形成的原因及消除方法[J].海洋地质与第四纪地质,2009,29(5):145-152,8.基金项目
中国工程院重大咨询项目"新疆可持续发展中有关水资源的战略研究",国家自然科学基金项目(40472094,40024202) （40472094,40024202）
