Ring Shear Test Analysis of Interface Shear Behaviour Between Saturated Silty Soil and Concrete

To analyse the shear behaviour of the interface between saturated silty soil and concrete of different roughness, this study improved the ring shear device and consolidation sample preparation device. Five concrete contact surface loading plates of different roughness were produced based on the different coarse aggregate particle sizes of concrete. We designed the interface ring shear test with different roughness in mind and whether the samples contained mud skin. Then, by analysing the test results, we reached the following conclusions: (1) The critical roughness R cr exists. When the roughness R was less than the R cr , the peak stress of the concrete–saturated silty soil interface increased with an increase in the roughness. When the roughness R was greater than R cr , as the roughness increased the peak shear stress of the concrete–saturated silty soil interface fluctuated around the shear strength of the soil and did not change significantly with changes in roughness. Before reaching the R cr , the friction angle of the concrete–saturated silty soil interface was approximately proportional to the log of the concrete roughness, ln( R ). (2) After adding mud skin, the stress–strain curve shows an obvious softening phenomenon, the peak shear stress being greatly reduced. Moreover, the presence of mud skin also changed the R cr . (3) Analysing the volume deformation, a large R promoted shear shrinkage and a large normal stress inhibited it. In addition, there was no obvious dilatancy during the test.