提高室内击实试验精确度的方法研究

Study on Accuracy Improvement of Laboratory Compaction Experiment

针对室内标准击实试验,介绍了压实度的确定方法和室内击实试验方法的选用,对影响试验结果的因素进行了说明和分析研究。首先对试验用土提出了要求,其次提出了击实土余土高度控制在6 mm内的"精确边击边测"的控制方法,控制每层土样击实后厚度约为三分之一筒高,当超过或欠缺时,应适当的减小或增加下层土的加入量,实践表明"精确边击边测"的控制方法可以有效的控制余土高度在6 mm以内。实验数据的处理借助Excel和Matlab软件,分别采用三点二次和更高次的Lagrange插值对最大干密度与最佳含水率进行求解。计算结果表明,并非选取的插值点越多、拟合曲线次数越高,就能达到更高的准确性,采用合理的三点二次的Lagrange插值法就可得到准确的计算结果。

This paper discusses how to determine compaction degrees and how to choose laboratory compac-tion experiments,then analyzes the factors that influence the experiment results. Firstly,the requirements for the experiment soil are set forth;Secondly,in order to control the excess height of soil column within 6mm,an experiment method called“controlling the excess height of soil column with compaction by accurate measur-ing”is proposed to control the thickness of each layer of soil sample reaching about one-third of the tube after compaction. When the height of each layer is higher or lower than one-third of the tube,the amount of added soil in the next step should be decreased or increased accordingly. The empirical study shows this method can effectively control the excess height of soil column within 6mm. In addition,with the aid of Excelland Matlab software,Lagrange interpolated with quadratic polynomial and high order polynomial is adopted to get the max-imum dry density and optimum moisture content. Results suggest that the accuracy of the result is not related to the numbers of interpolation points and high-order curve-fitting. Instead,Lagrange interpolated with quadratic polynomial in which three number points are reasonably selected will lead to accurate calculation results.