Evaluation of the Effectiveness of a Granular layer in Preventing Clogging and Blinding of Filter Geotextiles by Clay and Silt size Soil Particles in Sub-soil Drainage Systems

Abstract

Geotextile filters are frequently used in filtration and drainage applications for road pavement and structural drainage. These filters are prone to clogging by clay and silt particles. A study to evaluate the effectiveness of using a granular layer or washed river sand between the filter and base soil was conducted. A sandy clay soil was used in this study to investigate the performance of various geotextiles in soils with high clay and silt fractions. Two filtration tests with a total duration of 888 hours each were conducted. One test was conducted with 40 mm granular layer between the geotextile filter and the soil sample. The second test was conducted without a granular layer. The purpose of the two tests was to evaluate the effectiveness of the granular layer to maintain flow through a problematic soil and geotextile combination. The results of the study indicated that the granular layer maintained significant flow volumes, although towards the end of both tests partial clogging conditions appeared.