Shearing Characteristics of Mortar–Rock Binary Medium Interfaces with Different Roughness

Abstract

This study focuses on the crucial role of the shear characteristics of the mortar–rock interface (MRI) in geotechnical engineering. These properties largely determine the effectiveness of engineering reinforcement measures such as anchoring and grouting. The mechanical and deformation properties of the MRI with different roughness characteristics will be investigated. To achieve this, an indoor direct shear test was conducted on the mortar–rock binary medium (MRBM). The interface was numerically modeled from the test data using finite difference fractional value software. Direct shear simulation of the MRI by changing the normal stress (σn) and the sawtooth angle (α) was carried out. The results showed that as the normal stress and sawtooth angle increased, the shear stiffness of the MRI also increased. The shear stiffness was found to have a linear relationship with both the normal stress and the sawtooth angle. The peak shear displacement was identified as an indirect indicator of the shear failure mode of the binary medium interface (BMI). Quantitative relationships between the shear strength (τ), cohesion (c), angle of internal friction (ϕ), residual shear strength (τr), residual angle of internal friction (ϕr ), and degradation rate of the shear strength of the BMI were established based on the two influencing factors. Additionally, the study investigates how the sawtooth angle and the normal stress affect the variation in the normal displacement during direct shear testing of the MRBM. The findings revealed a correlation between the peak dilation angle of the BMI and the normal stress and sawtooth angle.