EDG无核密度仪标定模型与测试误差的试验研究

Experimental study of soil model and test error of electronic density gauge

EDG无核密度仪是一种无损快速的压实土干密度测试仪器,其在国内的应用经验较少。为研究EDG法干密度测试的准确性和适宜性,从EDG的测试机制出发,基于黄土试样的EDG法、灌砂法和烘干法测试结果,分析EDG法干密度测试产生误差的原因,以及测试误差大小。结果表明土的复合阻抗和电容电阻比均受密度和体积含水量两者的影响是造成EDG法测试产生误差的原因;EDG法干密度测试的误差大小并不是恒定值,而是在某些特定含水率和干密度区间内测试误差较小,其他区间测试误差较大;保证土料的均匀性,控制土料的含水率在较小区间内变化是EDG法干密度测试适用的前提条件;工程实践中宜针对采用的标定模型进行测试误差分析,明确标定模型适用的含水率和干密度范围。

Electronic density gauge（EDG） is a test instrument which could determine the dry density quickly and nondestructively. However the domestic application experience is rare. The measured results of loess with good homogeneity using the sand cone method,the oven-drying method and EDG were analyzed and the reasons causing the errors in EDG were found,so that the accuracy and the applicability of EDG in determining the dry density were determined. The impedance and the ratio of the capacitance over the resistance were all influenced by the density and the volumetric moisture,which was found to be the main reason causing the measurement error of EDG. The error varied with the dry density and water content. The error was smaller when the dry density and water content of the sample were within a particular range. Outside the range,the error was larger. Keeping the soil uniformity and moisture content changing within a small range are the premise of guaranteeing the accuracy of EDG measurement. It is necessary to analyze the error distribution of the soil model used in practice,and to confirm the application scope of dry density and water content to ensure a small error.