Laboratory study of geotextiles performance on reinforced sandy soil

This paper presents the results of triaxial tests conducted for the investigation of the influence of geotextiles on stress-strain and volumetric change behaviour of reinforced sandy soil. Tests were carried out on loose sandy soil. The experimental program includes drained compression tests on samples reinforced with different values of both geotextiles layers (Ng) and confining pressure (sigma'(c)). Two methods of preparation were used: air pluviation (AP) and moist tamping (MT). Test results show that the geotextiles induce a quasi-linear increase in the stress deviator (q) and volume contraction in the reinforced sand. Method of preparation significantly affects the shear strength; samples prepared by the air pluviation method and mobilized deviator stresses are significantly higher than those prepared by moist tamping method. Geotextiles restrict the dilation of reinforced sandy soil and consequently the contraction increases. The mobilized friction angle increases with increasing number of layers and decreases with increasing initial confining pressure. Samples prepared by moist tamping present mobilized friction angles significantly lower than those prepared by air pluviation method. For samples prepared by the air pluviation method, the secant modulus at epsilon(1)=1% and 5% decreases with increasing geotextile layers; those prepared by the moist tamping method, secant modulus at epsilon(1)=1% and 5% increases with increasing number of geotextile layer sand confining pressure. From 10% axial strain, secant modulus increases with increasing inclusions of geotextile layers.