A Method for Measuring Saturated Hydraulic Conductivity in Anisotropic Soils

Abstract

Saturated hydraulic conductivity (Ks) is an important soil parameter that is difficult to measure, especially in an anisotropic medium. Many methods for determining Ks have been developed over time, but taking different water flow directions into consideration is possible in only a few of them; furthermore, these few methods cannot be universally applied. The method proposed here allows Ks to be determined in both anisotropic and heterogeneous soils. It involves testing cubic soil cores using the Wit apparatus. To use this permeameter for samples that are not cylindrical in shape, it is necessary to prepare special measurement equipment. One such set of equipment developed consists of the soil cube (four sides of which are sealed with gypsum), which is placed in a protective box and connected to a measurement cuboid. In the soil sample, water always flows from the bottom up during the test, but it is possible to turn the sample over and thus analyze different water flow directions. The soil cubes needed are small (0.05 by 0.05 by 0.05 m), but for a particular set of conditions only 15 cores extracted from each sampling location was found to be enough to determine Ks with a precision of ±15%. Results yielded by the presented method appeared to be comparable with Ks values obtained using a constant‐head permeameter with cylindrical soil cores. The advantages of the proposed technique are the possibility of measuring Ks in both horizontal and vertical directions using the same sample, a lack of leakage along the edges of a sample, the ease of soil sample extraction, and the technique's use of inexpensive materials.