Experimental investigation of shearing behavior at cohesive soil-geotextile interfaces

The results of direct shear tests on unsaturated silty clay samples reinforced with woven and nonwoven geotextiles were analyzed in terms of both overall strength increase and interface bond development. It was found that the strength increase under low values of normal stress showed a drained behavior whereas higher normal stresses resulted in undrained behavior. The magnitude of interface bond - combined friction and adhesion - increases with the water transmissivity of geotextile and depends on the normal stress. Graphs are presented relating interface friction angles compatible with the expected values of adhesion efficiency for the geotextiles used in the investigation.