颗粒分析试验研究

Experimental Study of Gradation Test

颗粒分析试验是测定干土中各种粒组所占该土总质量的百分数的方法,借以明了颗粒大小分布情况,供土的分类及粗略判断土的工程性质及建筑材料选料之用,其中的密度计法用于测定小于0.075mm以下的颗粒大小及分布情况,测量的准确度直接关系到土中黏粒和胶粒的多少,在试验的角度分析了密度计法试验结果误差的原因,指出现行规范中温度校正的不合理性,提出了空白试验方法,供工程技术人员和土工试验人员参考并验证。

Gradation test is used to get the dry mass percentage of various sizes of soil particles. This is the typical test to obtain the actual soil particle size distribution curve. The curve is usually utilized as a preliminary approach to estimate the soil engineering property or used in determining the applicability of backfill materials. A significant component of the test is hydrometer analysis which is used to get distribution for the soil particle with size less than 0. 075mm. However,hydrometer test result is usually different even for the same sample by different operators or laboratories. The hydrometer is the most direct ap- proach to obtain the percentage of silt and clay particles although its result is very sensitive to the temperature or its accuracy depends on various factors. This paper is to investage the background of the errors from the stand point of testing and to sum- marize the misunderstandings of temperature correction method in the current code. A KONGBAI approach is finally recom- mended in eliminating or reducing the hydrometer analysis errors. This method can be used as a reference in engineering and can be testified by future lab testing.