Laboratory and theoretical study for concrete–mudstone interface shear to account for asperity degradation.

In this study, laboratory tests have been conducted to investigate the performance of concrete–mudstone interface shear under constant normal stiffness (CNS) condition and the profile of the interface roughness is assembled by using a series of identical triangular asperities. Direct shear tests on the samples are carried out under CNS conditions, with special emphasis on the different initial normal loads and normal stiffnesses provided by parallel springs. The observations indicated that the shear behavior is highly dependent on the compressibility of asperities. Based on energy principles, the authors have developed an alternative degradation function to account for the mobilized dilation angle, where the material and geometric indexes were introduced for correlating the shear strength with the properties of mudstones. The proposed model relates the normal and shear stresses to the corresponding displacements in terms of the material properties, asperity inclination and chord lengths. In addition to the predictions of strength, the degradation patterns could be also concluded by imposing varying material and geometric indexes. Results from the proposed method is verified by experimental observations and the comparison appears to be satisfactory. Sensitivity study was also carried out for demonstrating the application of the proposed method. [ABSTRACT FROM AUTHOR]