ABSTRACT
In order to determine the hydraulic conductivity in unsaturated soil, more complex experimental methods are required than in saturated soils. As in saturated soils, these methods can be performed in transitory or stationary conditions. Existing techniques to determine the permeability of unsaturated soils can be broadly categorized in three main methodologies. The first one, the so-called Gardner’s method (Gardner 1956), proposes the use of the Richards’s cell (Richards 1931). This method determines the hydraulic conductivity in transitory conditions. It consists in measuring the time evolution of the water volume that moves out of the sample due to a gas pressure increment, which in turns means a suction increment, as the suction s = pg − pw where pg and pw are the gas pressure and the water pressure, respectively.
