Changes in the Soil Moisture Characteristic due to Porosity Variation

Compaction during construction will reduce the overall pore volume of soil and change the size and distribution of the pores within the soil. The resulting pore space changes are expected to change the moisture characteristic of the soil. The soil moisture characteristic has been examined using experiments where a single soil type was tested for a range of porosity values. Moisture characteristic data recorded in published papers and measured at the University of New Mexico were evaluated. A new term, the Moisture-Density Variation Ratio, was used to quantify the relationship between the dry bulk density and the unsaturated soil moisture. The test data was used to predict changes in the soil moisture characteristic with changes in the porosity. A method is presented to modify the parameters in the van Genuchten soil moisture characteristic equation with changes in porosity or dry bulk density.