土的两种塑限测试方法精密度比较

Comparison of the precision of two plastic limit testing methods of soil

塑限是土的重要的物理指标之一,为了比较液塑限联合测定法和滚搓法这两种土的塑限测试方法的精密度,按照《测量方法与结果的准确度(正确度与精密度)》第2部分(GB/T6739.2)的规定,制备了5个水平的样品,组织9家实验室开展了精密度协作试验。采用曼德尔统计法、科克伦检验和格拉布斯检验对测试结果进行了一致性和离群值的检验,剔除2组离群值后,依据《测量方法与结果的准确度(正确度与精密度)》第6部分(GB/T 6739.6)对两种塑限测试方法进行了精密度比较,最后给出了不同技术活动中选择塑限测试方法的建议。研究结果表明:重复性方差Sr2和再现性方差SR2与样品塑限水平没有依赖关系,部分样品的实验室内精密度显示滚搓法优于液塑限联合测定法,两种方法的总精密度无显著性差异。

Plastic limit is one of the important physical indexes of soil. In order to compare the precision of two plastic limit determination methods of soil,i.e. Atterberg limits testing and the rolling method,5 levels of samples are prepared according to the provisions of the national standard GB/T 6739. 2,and 9 laboratories are organized to carry out the precision collaboration test. Mandell statistical method,Cochrane test and Grubbs test are used to test the consistency and outliers of the test results. After the two groups of outliers are eliminated,the precision of the two testing methods is compared according to national stanard GB/T 6739. 6. Finally,suggestions to select the plastic limit test method in different technical activities are recommended. The results show that the repeatability variance Sr2 and reproducibility variance SR2 are independent of the plastic limit level of the samples,and the laboratory precision of some samples show that the rolling method is superior to the liquid-plastic limit combined measurement method. There is no significant difference in the total precision of the two methods.