Abstract:In order to study the effect of particle shape on shear behaviors of interface between coarse-grained soil and geogrid, the gravel and glass beads with the same particle size distribution were selected as test materials.A series of monotonic direct shear tests, cyclic shear tests and post-cyclic direct shear tests were carried out on the gravel-geogrid interface and glass bead-geogrid interface using a dynamic direct shear apparatus. The monotonic direct shear characteristics of the interface between reinforced gravel and reinforced glass beads under normal stresses of 30, 60, 90 kPa were analyzed. Then, the cyclic shear characteristics of two reinforced interfaces under cyclic loading with displacement amplitudes of 1, 3, 6, 9, 12, 15 mm were studied.The similarities and differences of monotonic shear characteristics of the two reinforced interfaces before and after cyclic shear were compared and analyzed. The results show that in the monotonic shear tests, the shear strength and maximum dilation of gravel-geogrid interface under the three types of normal stresses are greater than the corresponding values of glass beads-geogrid interface. In the cyclic shear tests, the cyclic shear behaviors of gravel-geogrid and glass beads-geogrid interfaces under the cyclic loading with different shear amplitudes are not exactly the same. In the post-cyclic direct shear tests after cycling, the interface shear strength of gravel-geogrid interface after cycling is greater than that of the interface without cyclic loading, except for the interface with amplitude of 15 mm, while the corresponding value of glass beads-geogrid interface at all amplitudes is degraded.