Effect of Fines on Strength of Granular Soil Reinforced with Geosynthetics

Abstract

Geosynthetics (GSN) are polymeric products used in Geotechnical Engineering for the purpose of improving the properties of the insitu soil. In this project, experimental work was carried out to determine the influence of presence of fines within granular soil on the CBR strength of soil reinforced with different GSN (Woven geotextile, Non-woven geotextile, Geogrid and Geonet). Two types of granular soil in disturbed state containing varying percentage of fines were selected from in and around the Chennai region. Soil type 1 contains high fines of about 40% (SHF) whereas soil type 2 contains less fines of about 7% (SLF). Unsoaked CBR (U-CBR) test was carried on unreinforced soil and on soil reinforced with different GSN placed at varying depths of D/5, 2D/5, 3D/5 and 4D/5 from top of soil (D is the total depth of soil), to determine the ideal depth of placement of GSN within SHF and SLF. Soaked CBR (S-CBR) test was carried on unreinforced soil and on soil reinforced with different GSN placed at an ideal depth determined from U-CBR test. Based on the experimental results, ideal depth of placement of GSN for SHF and SLF was found to be D/5 and 3D/5 respectively from top of the soil and Geogrid was found to be the best geosynthetic for reinforcing the granular soil containing high fines and less fines.