EM-Wave Based Characterizations of Local Void Ratios in Soils

The distribution of local void ratios rather than a single average value is more pertinent to soil's behavior, and different techniques have been applied to quantitatively assess this spatial variation. In this paper, a method based on the local permittivity of soils measured at 1 GHz and associated mixing rules, is used for the same purpose. The local permittivity along the soil specimen is gauged using a slim form probe with an outside diameter of 2.2 mm. The experimental results on saturated soil specimens indicate that this technique is a simple and useful tool to evaluate the spatial variability of soils. Yet, the validity and suitability of mixing rules to soil-water mixtures, as well as the measurement limitations, require further study.