2014 Volume 70 Issue 1 Pages 83-95
This study proposes a new laboratory testing method for unsaturated zone air permeability, which is the dominant factor for air flow in unsaturated zones, under the condition of higher degree of saturation. The method applies the instantaneous profile method, which is an unsteady state method for measuring an unsaturated hydraulic conductivity in laboratory. To measure accurately fluctuations of unsaturated pore air pressure with extremely high water content, pore water pressure should be separated. Two new types of filters, PTFE filter and water repellent coating filter, are evaluated as an alternative to traditional glass filters, which cannot separate these pressures. As a result, the gas phase pressure detected with these new filters is sharply separated from the liquid phase pressure in unsaturated soil. Theoretically, this new testing method with the instantaneous profile method can measure both water permeability and air permeability for evaluating two-phase flow simultaneously.