MSW介质含水率与介电常数的关系模型试验研究

Model tests on relationship between water content and dielectric constant of MSW media

时域反射测量(TDR)利用水的介电常数与岩土介质介电常数差异较大的特点,由电磁波反射波形分析得到岩土介质的介电常数和电导率,并通过经验关系换算获得含水率。目前,在岩土工程领域采用TDR测试含水率的研究及应用多局限于土介质,很少有关于城市固体废弃物(MSW)方面的研究。采用一种基于表面反射法原理研制的四针式TDR传感器,通过室内标定试验建立MSW介质含水率与其介电常数的经验关系模型,该模型考虑了介质孔隙率的影响,基于该模型的TDR测试结果与烘干法测试结果的误差不超过±5%。

The time domain reflectometry(TDR)takes advantage of the large difference of dielectric constants between water and soils.The dielectric constant and conductivity of soils are obtained from the analysis of the electromagnetic wave reflection waveform,and the water content of soils is obtained through empirical conversion.At present,the researches and application of using TDR to test the water content in the field of geotechnical engineering are mostly limited to soil media,and there are few studies on the municipal solid waste(MSW).In this study,a four-pin TDR sensor developed based on the principle of surface reflection method is used to establish an empirical relationship model between the water content of the MSW media and their dielectric constant through indoor calibration experiments.This empirical relationship model takes into account the influences of the porosity of MSW media.The error of the test results between the TDR technology based on the above empirical relationship model and the drying method does not exceed±5%.