INFLUENCE OF PARTICLE-SIZE GRADATION ON SHEAR BEHAVIOR OF GEOSYNTHETICS AND SAND INTERFACE

A series of large scale direct shear tests,involved three different particle-size gradations of sands with geogrids and geotextiles,were performed to investigate the interface shear strength and dilatancy of soil against geosynthetics. The effect of particle-size gradation,dense degree,types of geosynthetics and vertical stress on interface shear strength and dilatancy coefficient were investigated. The test results show that coarse sand and fine sand/geosynthetics interface have significantly higher shear strength than their mixed sand. Loose sand-geosynthetics interface displays only shear contraction during the shear process;while dense sand-geosynthetics interface presents obvious dilatancy. At the high stress level,sand-geosynthetics interface has larger shear displacement when it reaches peak shear strength than that of low stress. Coarse sand-geogrids interface has larger shear displacement when reaching peak strength than that of coarse sand-geotextile;while fine sand-geosynthetics interface shows the opposite results.