AN EXPERIMENTAL EVALUATION OF FABRIC STRENGTH PROPERTIES AND BEHAVIOUR OF FABRIC REINFORCED SOIL

Abstract

The strength and the stress-strain properties of fabric reinforcement under various test conditions, the soil-fabric interface frictional resistance and the soil-fabric composite behaviour have been investigated. Different types of tensile test are carried out on high strength woven polyester fabric (i) unconfined uniaxial tensile test on yarns, narrow strip and wide strip specimens and (ii) confined uniaxial tensile test on wide strip specimens under different confining pressures. The strength and stress-strain results of these tests have been compared to determine the behaviour of the fabric and the effect of confinement on the strength and stress-strain properties of the fabric. The interface friction angle of sand interacting with cotton gauze and polyester fabric under different normal pressures was investigated by direct shear box tests as well as the effects of the relative size between sand grains and fabric openings. The soil-fabric composite behaviour was also studied by triaxial tests on 100 mm and 200 mm diameter unreinforced and reinforced samples at different confining pressures. The reinforced samples are prepared with both woven and non-woven fabric layers at different spacings. In the 200 mm diameter samples strain gauges are mounted on the fabric layers to determine the strain distribution in the fabric. Two analytical models have been proposed. The first model was developed to determine the strength and stress-strain properties of fabric reinforcement from triaxial tests. The second model can be used to estimate the strength of the fabric reinforced triaxial sample taking into account the effects of fabric spacing, fabric stiffness and the applied confining pressure on the mobilised interface friction along the fabric and the modes of failure.