The compaction degree is an important parameter for evaluating the quality of soil compaction in many engineering constructions such as roads

housing construction

and water conservancy project

and it correlates with moisture content and electrical conductivity. Frequency domain reflectometry (FDR) can rapidly measure soil moisture content and electrical conductivity. Firstly

in this research

FDR was adopted to rapidly measure the values of soil moisture content and electrical conductivity regarding lateritic soil

expansive soil

and loess at varying compaction degrees. Secondly

the measured values of moisture content were calibrated in laboratory

and the calibration curves of the three soils were obtained accordingly. Thirdly

empirical relationships between compaction degree

moisture content and conductivity of the three soils were established using the partial least squares regression (PLSR) analysis method

and compared with the measured value. Fourthly

scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests revealed its mechanism from microscopic aspect. Finally

the predicted value of the compaction degree obtained by the fitting equation was verified

and an error evaluation system was established. The results show that such fitting equations based on the relationship between compaction degree

moisture content

and electrical conductivity have a high prediction accuracy. Therefore

the results in this work can provide a good reference for the rapid detection of soil compaction in roads

housing construction

water conservancy and other projects.