Abstract: In order to investigate the behavior of reinforcement-soil interface under dynamic load, a series of cyclic direct shear tests focused on geogrid，woven geotextile，non-woven geotextile with sand interface are performed through large-scale direct shear device. The shear stiffness and damping ratio of the interface in different conditions are gained; and then the relationship between cycle number and shear stiffness or damping ratio are analyzed. Results show that, in the same cycle number, the geogrid-sand interface has the largest value of shear stiffness; and the woven getextile-sand interface has the largest value of damping ratio. The interface exhibit cyclic shear hardening in the three values of normal stress with the cyclic shear amplitude of 3 mm. The damping ratio of the interface in different normal stresses tends to a same stable value with the increase of cycle number. The interface shear stiffness is increased and damping ratio is decreased with sand relative density, and with the increase of cycle number the damping ratio of the interface in different sand relative densities tends to a same stable value. Cyclic shear degradation is observed in the interface suffering cyclic direct shear with shear amplitude of 5 mm; the interface with a larger shear amplitude in cyclic direct shear has larger value of stiffness.

Key words: reinforced soil, reinforcement-soil interface, cyclic shearing, shear stiffness, damping ratio