含水率对粘性土击实干密度的限制作用分析

Analysis on Restrictive Effect of Moisture Content upon Compactive Dry Density of Cohesive Soil

粘性土的击实试验是各类岩土工程试验规范中规定的最基本的土力学试验,目的在于求取一定击实功能下土的最优含水率和最大干密度,试验结果不但可以直接用于指导工程建设实践,而且一些重要工程的其它力学指标的准确获取也大都是在击实试验结果确定的条件下进行的,因而粘土击实试验结果的准确获取十分重要。采用土体饱和度计算分析法,对某击实土体饱和度大于100%这一不合理现象进行了计算分析。找到了问题存在的根源在于没有考虑粘性土中水对土体干密度的限制作用。提出了含水率对粘性土击实干密度具有限制作用的结论,即粘性土的最大干密度不会超过土体被击实达到饱和状态的干密度。

The compaction test of cohesive soil is one of the most basic soil mechanics experiments in various types of geotechnical engineering test specifications,the aim of which is to obtain the optimal water content and maximum dry density under a certain compactive effort.The test results could not only be directly used to guide the engineering constructions,but some other mechanical indexes are also obtained with the compaction test results,therefore,it is particularly important to achieve the accurate compaction test results.Here,by using the soil saturation analysis method,the reasonable calculation and analysis are made for a compacted soil whose saturation coefficient is greater than 100%.The results show that the root cause of problems is not to consider the restrictive effect of the water in clayey soil upon the soil dry density.And it is proposed that the percent moisture content has certain limits on the clay dry density,that is,the maximum dry density of clay soil would not exceed the maximum dry density in saturated state of the compacted soil.