Experimental Investigation and Constitutive Modeling of Rock-Like Specimens' Interface with the Effect of Roughness Based on 3D Printing

The response of a structure-foundation system subjected to loading is a function of the interaction between them. If the response is to be analyzed accurately, the effect of roughness at the interface needs to be considered. This study is an investigation of the interface behavior of concrete (rock-like) specimens with four different surface roughnesses, experimentally and numerically. To provide roughness at the interface, an innovative three-dimensional (3D) printing technology was used to create roughness on the surface of concrete specimens. A series of uniaxial compression, interface normal compression, monotonic, and one-way cyclic shear tests was performed. The disturbed state concept (DSC) constitutive model was used to define the interface behavior under shear deformation by simulating both prepeak and postpeak behaviors, including microstructural modifications and softening in deforming materials. The results of the interface tests were used to determine the parameters of the DSC model. These parameters were obtained as dependent on both surface roughness Rs and joint roughness coefficient (JRC) at the interface. DSC parameters, such as normal and shear stiffnesses, and ultimate, phase change, hardening, and disturbance parameters, were derived as functions of Rs and JRC . The friction angle variation with JRC was also determined and validated with a high accuracy. The foregoing are some of the novel aspects in this study. The resulting parameters were used to validate the DSC model by back-predicting both the tests that were used for determining the parameters and the independent tests that were not used for parameter determination. Satisfactory correlation was observed between computational predictions and test measurements.