DETERMINATION OF WATER HYDRAULIC CONDUCTIVITY FUNCTIONS OF UNSATURATED SOILS

摘要

Reliable measurements and predictions of unsaturated hydraulic conductivity functions are essential for solving unsaturated flow problems. Over the years a number of testing techniques have been suggested for determination of water hydraulic conductivity functions of unsaturated soils. The main goal of this paper is to provide an overview of these methods. Details as to the procedures for conducting the laboratory tests are not presented in this paper. These are given in the various papers cited. The focus is on the inherent advantages and shortcomings of each technique, and on an examination of the underlying assumptions. The testing techniques reviewed include direct and indirect methods. This paper also presents an approach called the inverse problem solution for determining permeability functions In this approach the experimental data is viewed as the solution to the boundary value problem for which the governing equation and the initial and boundary conditions are known, but the material functions and the parameters in the governing equations are unknown. Since the inverse solution problems are usually mathematically "ill posed", the quality of the experimental data is essential to the success of this approach (Znidarcic et al. 2004).