Hydraulic Properties of Unsaturated Soils: A Novel Procedure

Buildings built on shrink-swelling soils may experience serious damage due to volumetric strains. These strains are produced by drying-wetting cycles generated when water content fluctuates in the mass of soil. In order to study this behavior, theoretical models taking into account the soil-water retention curve have been developed. The retention curve is used to indirectly estimate some parameters describing the hydraulic behavior of soils, as for example the hydraulic conductivity and the diffusion coefficient. The precision of indirect methods to determine the hydraulic parameters depends largely on the accuracy of the experimental points of the soil-water retention curve and the equations used to simulate this curve. However, it is possible to skip the second step and simply use the experimental data of the characteristic curve to obtain these parameters. Therefore, a procedure based on an interpolation method with variable increments is proposed. This procedure generates a polynomial equation for the retention curve which simplifies the method and avoids errors caused by the fitting process of the theoretical with the experimental retention curve. In addition, no fitting parameters are required with this procedure. The results obtained with this method are similar to those reported by the traditional indirect methods.