Effect of Shear Displacement Amplitude on the Cyclic Shear Properties of the Gravel-geogrid Interface

Abstract

The dynamic shear performance of the soil-geosynthetics interface is receiving increasing attention since reinforced soil structures are subjected to cyclic loads over a prolonged period of time. The current cyclic shear tests are usually performed over a limited number of cycles, generally ten, which fails to fully reflect the dynamic interaction at the interface of geosynthetics reinforced soil. In this study, horizontal cyclic shear tests with 2 000 cycles were conducted on the gravel-geogrid interface with shear displacement amplitudes of 1 mm, 2 mm, 4 mm, and 6 mm. The effects of shear displacement amplitude on the shear stress, vertical displacement and particle fragmentation at the gravel-soil interface were analyzed, and the mechanism of interaction at the gravel-geogrid interface was proposed. The average peak shear stress at the interface was shown to increase and then decrease during the cyclic shear test. The results indicate that the larger the shear displacement amplitude, the fewer cycles are required to reach the peak strength of the interface, and more cycles are required to reach the residual strength of the interface. Larger shear displacement amplitude was shown to make the shear stress decay phenomenon at the gravel-geogrid interface more significant. Furthermore, as the shear displacement amplitude increases, the final shear shrinkage of the specimen increases, but the increment of the final shear shrinkage of the specimen gradually decreases. Moreover, as the shear displacement amplitude increases, the shear stiffness of the interface gradually decreases, but the damping ratio of the interface gradually increases. By analyzing the content of each particle group of gravel particles after the cyclic shear test, it was found that with the growing shear displacement amplitude, the relative particle fragmentation rate also increased. Further, the relative breakage ratio showed a good logarithmic relationship with the shear displacement amplitude and was in good agreement with the test results.