六种不同前处理方法对陕北砂黄土粒度测量的影响

Influence of Six Different Pretreatment Methods on Grain Size Measurement of Sandy Loess in Northern Shaanxi Province

摘要: 不同前处理方法对沉积物粒度测试结果的真实性具有十分重要的作用。采取6种不同的前处理方法对陕北砂黄土运用激光粒度仪进行测量，探讨不同前处理方法对粒度测量的影响，以获取砂黄土准确的粒度分布情况。结果表明：经方法A和方法E处理后得到的黏粒含量平均值较大，分别为6.38%和6.10%；方法C和方法F的平均粒径Φ值都较小，分别为5.21Φ和5.08Φ，经过超声波、分散剂和HCl处理后的得到的黏粒含量不是真实的粒度测量结果。砂黄土中的有机质会对粒度测量产生较大影响，方法D得到的黏粒含量较小，为6.17%，粉砂粒含量较大，为69.19%，表明经过处理后细粒组分百分含量减少。单独加入H2O2的前处理方法得到的黏粒含量最多(6.75%)，平均粒径最细(5.29Φ)，分选性最差(1.82)，偏度最大(0.43)；与其他方法相比，分散效果更好。单独加入H₂O₂的前处理方法(文中B方法)粒度分散效果最好，更适用砂黄土的粒度测量。

Abstract: Different pretreatment methods play a very important role in the authenticity of sediment particle size test results. This paper adopted six different pretreatment methods to measure the grain size of sandy loess in northern Shaanxi Province by laser particle size analyzer, and the influence of different pre-treatments on grain size distribution was discussed. The results showed that the average clay content after treatment by method A and method E was larger, 6.38% and 6.10%, respectively; the average particle diameter Φ value of method C and method F are both smaller, 5.21Φ and 5.08 respectively Φ, the content of clay particles after ultrasonic, dispersant and HCl treatment is not the true particle size measurement result. The organic matter in the sandy loess will have a greater influence on the grain size measurement. The clay content obtained D the method is small, 6.17 and the silt content is 69.19, which indicates that the percentage content of fine grained component decreases after treatment. The pre-treatment method with H₂O₂ addition alone obtained the most clay content, which was 6.75%, and the average particle size was the coarsest, which was 5.29Φ, and the sorting coefficient and skewness were also the largest, which were 1.82 and 0.43, respectively. Compared with other methods, the median particle size was larger, the content of coarse particles was reduced, the content of fine particles was increased, the particle size become finer, and the dispersion effect was better. Therefore, the pretreatment method of adding H₂O₂ alone (method B in the paper) was more suitable for grain size measurement of sandy loess.