Performance evaluation of nonwoven geotextiles in soil fabric interaction

A laboratory research program was undertaken to determine the influence of fabric mass and normal pressure on the stress-strain characteristics of a geotextile-soil interface. Pullout tests were done in a large pullout box using three needlepunched nonwoven geotextiles with the same apparent opening sizes and different mass/unit areas. A dry medium sand was the cover material. Effects of mass/unit area of the fabric and normal pressure on pullout test results were analyzed in terms of ultimate pullout load and strain at different points on the geotextile specimens. Pullout tests were conducted at 7, 14, and 21 kPa normal pressures and at a constant displacement rate of 20 mm/min. Pullout resistance: decreased with increased geotextile mass/unit area due to extensive necking of the geotextiles. Pullout resistance also increased with increasing normal pressure. Effective embedment length was determined at each normal pressure level based on the strain developed along the length of the geotextiles.