Influences of shear rate and loading frequency on shear behavior of geogrid-soil interfaces

The reinforced soil structures are widely used in road engineering, and the influences of the dynamic load of vehicles on the interaction characteristics of geogrid-soil interfaces cannot be ignored. A series of direct shear tests on the gravelly soil-geogrid interface under normal cyclic loading are carried out using the dynamic direct shear apparatus. The influences of 4 shear rates (0.1, 1, 5, 10 mm/min), 4 cyclic loading frequencies (0.1, 0.5, 1, 2 Hz) and 3 normal initial stresses (20, 40, 60 kPa) on the shear behavior of the reinforced soil interface are studied. The test results show that the shear stress and normal displacement under normal cyclic loading change periodically. The upper peak stress, upper residual stress and amplitude of shear stress decrease with the increase of the frequency, increase with the increase of the shear rate, and the lower shear stress is less affected. The peak relative time shift of the shear stress and the normal stress is the largest when the frequency is 0.5 Hz or the rate is 1 mm/min, respectively, while the relative time shift of the friction coefficient and the normal stress is about 0.5 cycle. The upper peak friction angle decreases with the increasing frequency and increases with the increasing shear rate.