Vibro-induced weakening of interface friction between granular materials and textured surfaces: An experimental study with a modified direct shear apparatus

Underground structures below or adjacent to railway lines frequently suffer train-induced vibration. In order to better predict the structures’ performance under vibration, attention has been paid to investigating the behavior of soil-structure interfaces. Limited by the capabilities of current test apparatus, the soil-structure interface friction is mainly determined under static and quasi-static loading conditions. While the interface friction behavior under vibration has been rarely addressed, especially under high-frequency vibration. This study focuses on the frictional behavior of granular material-structure interfaces under coupled static and one-dimensional vibration loading, where influences of vibration intensity, frequency, normal stress, particle shape, surface roughness, moisture condition, and initial relative density are systematically analyzed. The results show that the vibration leads to friction weakening of the interface, showing as shear stress loss and shear displacement slip. For test conditions included in this study, the shear stress loss even reaches up to 50% of the shear stress prior to vibration. The friction weakening is found independent of the initial density when shearing at steady state. Critical values of water content and vibration frequency have been observed, where the shear strength loss and displacement slip reach their peaks.