Influence of Internal Friction Angle and Interface Roughness on Shear Behavior of Mortar-Rock Binary Medium Joint

The damage of the interface between mortar and rock often occurs in engineering projects. The stability of the binary medium joint is the key factor in judging the stability of a hydraulic structure foundation. The shear characteristics of the flat mortar-rock joint were numerically simulated under the direct shear test by finite element using FLAC3D software. The results showed that the internal friction angle of mortar has little influence on the shear strength, its corresponding displacement, strain softening degree and residual shear strength for flat joint. Therefore, considering the roughness of the structural surface, the joint with regular serrated mortar-rock binary medium was established in this paper, and the direct shear test under the condition of constant normal stress was carried out for comparative study. The results showed that the shear strength, residual strength, peak strength displacement and strain softening degree of the serrated structure were strongly correlated with the internal friction angle of mortar. For the regular serrated binary joint, improving the mortar performance can improve the shear performance and stability of the whole structure more effectively than the flat joint. The relationship between the shear strength, residual strength and the friction angle were established respectively.