Results of direct shear tests on geotextile reinforced cohesive soil

The results of direct shear tests on near-saturated silty clay samples reinforced with woven and nonwoven geotextiles are presented and analyzed in terms of the strength increase, shear and volumetric deformation of reinforced soil, and soil/reinforcement interface bond development. The analyses-which are based on total stresses-indicate that the inclusion of nonwoven geotextiles resulted in a significant strength increase of the wet cohesive soil. The inclusion of woven geotextiles, however, did not offer any strength increase. This differentiation of behaviour was attributed to the nil water transmissivity of the woven geotextile. By further analyzing the test results it was found that the magnitude of the interface bond increased with the transmissivity of the geotextile and varied with the normal interfacial stress. By utilizing a simple soil-reinforcement interaction model, values of interface friction angles were computed for different assumed values of adhesion efficiency between cohesive soil and geotextile. (C) 1997 Elsevier Science Ltd.