Friction behaviour of geotextile interfaces under cyclic conditions

The stability analysis of geotextile encapsulated-sand systems requires input on the shear strength behaviour of its interfaces. An experimental study on the friction behavior of different geotextile interfaces under cyclic conditions is important for that purpose. This paper presents the results of a large-scale direct shear test series where geotextile sheets and sandbags were employed as samples. Cyclic loading shear tests indicated that an increase in the frequency of excitation slightly increases the shear strength and friction angle, whereas an increase in the range of load variation reduces the shear strength at peak and gently increases the post-peak resistance. Cyclic displacement-controlled tests revealed a shear stress increase in the first cycles which depends on the amplitude of displacement imposed, however, after a larger number of cycles the interface shear strength converges for different amplitudes of displacement. This paper also provides preliminary results from a widerset of direct shear testing with sandbags, which is currently being carried out. From those results it was concluded that the shear strength is significantly higher in the tests with sandbags than in those with the geotextile interfaces only