Evaluation of the effects of the hydraulic gradient variation on the permeability of a compacted soil

Abstract

The present study evaluated the influence of the hydraulic gradient on soil conductivity changes using data from permeability tests performed in a column percolation test system, in order to represent geoenvironmental engineering applications. A mature residual soil from gneiss, pedologically classified as Red-Yellow Latosol, with 67% of clay, 10% of silt, 23% of sand, 82% of liquid limit and 46% of plastic limit was used in the study. Soil specimens were compacted at the optimum compaction parameters determined at the Standard Proctor effort, i.e., wopt =31.37% and γdmax =13.54 kN m-3. After compaction, it was determined the permeability of specimens under the hydraulic gradients of 15, 66, 85 and 140. The results obtained support that: (i) at the 5% level, there is statistical significant variation in the permeability coefficient according to the hydraulic gradient used in the tests; (ii) from a geotechnical perspective, there is a slight tendency of increasing the permeability coefficient when increasing the hydraulic gradient, but of no significance for geotechnical practical applications.