细粒土界限含水率液、塑限联合测定自动化方案的分析与探讨

为解决现行细粒土界限含水率液、塑限联合测定法效率低下和试验流程难以自动化的难题,通过对现行液、塑限联合测定法试验原理的扩展应用进行讨论,得出无论是对烘干土还是天然土试样进行液、塑限联合测定,都可通过监测土膏调制过程中水的增量求得各级土膏含水率,而无需对各级土膏采用烘干法逐级测试含水率的结论,并给出了试样干、湿2 种状态下求解各级土膏含水率的计算方法;以此为基础,结合昆明轨道交通4 号线岩土勘察获取的大量细粒土液、塑限联合测定试验操作的计时观察结果,对现行试验方法系统功能进行优化分析,进而得出界限含水率试验的优化流程。该流程人工操作时长可减少75%,完成单组试样界限含水率测试所需时长??t 可由16. 5 h 缩减为6. 5 h。根据优化试验流程和试验方法特征,提出液、塑限闭式联测法这一自动化实现方案,并对其试验应用条件进行初步讨论。

Analysis and Discussion on Automatic Scheme of Combined Determination of Liquid and Plastic Limits for Limit Moisture Content of Fine-grained Soil

The efficiency of the current combined determination method for liquid and plastic limits for the limit moisture content of fine-grained soil is low, and the automation of the test process is difficult to be realized. Hence, an extended application of the test principle of current combined determination method of liquid and plastic limits is discussed. It is concluded that the water content at each grade of soil paste can be obtained by monitoring the water increment in the process of preparation of soil paste, and it is not necessary to use only the drying method to test the water content of each grade of soil paste. Moreover, the calculation methods for moisture content of soil paste at all levels by using both dry and wet samples are put forward. Thus, on the basis of a large number of observed test operation timing results via the combined determination method of liquid and plastic limits of fine-grained soil in the survey process of Kunming Rail Transit Line 4, the evolution analysis of the current test method system function is made, and the optimized limit moisture content test process is obtained. The optimized process can reduce the man-machine operation time by 75%, and the time required to complete the limit moisture content test of single group of samples can be decreased from 16. 5 h to 6. 5 h. According to the characteristics of the optimized test flow and test method, the automatic realization scheme of liquid and plastic limit closed joint test method is put forward, and the test application conditions are preliminarily discussed.