# Numerical Analysis for Shear Behavior of Binary Interfaces under Different Bonded Conditions
###### Abstract  
The shear performance of the binary interface formed by mortar and rock cementation is a key factor influencing the stability and safety of basic engineering projects related to livelihood and economy since concrete has become one of the most widely used materials in engineering. Therefore, it is an urgent practical problem to further explore and clarify the shear failure mechanism of the mortar-rock binary interface. In response to the current research objective focused on fully bonded interfaces, this paper constructed binary interface models with different bonded conditions to perform direct shear experiments using numerical simulation methods, and the effect of bonded conditions on the shear behavior of the mortar-rock binary interface was analyzed. The results indicate that the bonded conditions have a significant influence on the shear mechanical behavior of the mortar-rock binary interface, which is mainly reflected in the stress-displacement curve characteristics, the shear strength, the fracture development and the stress distribution state. The research findings are of great theoretical significance for the further study of shear mechanics at the mortar-rock binary interface and of great practical significance for safe construction, resource conservation and disaster warning. [PERSON] [11] used a combination of experimental and numerical methods to analyze the propagation law of stress waves and revealed the damage mechanism of the mortar-rock interface. [PERSON], [PERSON] [12] established a quantitative relationship between the sawtooth angle and the shear strength of the rock-mortar interfaces through the AE technique, and three AE characteristic parameters that can be used to predict interface failure were proposed. Numerical simulation methods, such as discrete element and finite element analyses, were also widely used in their research [13]. [PERSON], [PERSON] [14] carried out simulations of the shear mechanical behavior of a weak interlayer between two rocks with high strength differences and proposed an equation on the relationship between the roughness coefficient parameter and surface statistical fractal parameters. [PERSON], [PERSON] [15] investigated the shear strength, shear expansion, and damage behavior of binary interfacial specimens with different bond strength ratios under different normal stresses. [PERSON], [PERSON] [16] found that the shear stress at the mortar-rock interface was much smaller than that at the bolt-mortar interface for bolted rock slopes containing weak interlayers, and the shear stress distribution and the debonding damage process at the bolted interface of slopes under seismic action were obtained. [PERSON], [PERSON] [17] proposed a criterion for crack extension of layered mortar-rock beams based on the stress-intensity factor and, on this basis, presented a numerical method to predict the crack extension process of laminated mortar-rock beams under type I fracture. [PERSON], [PERSON] [18] examined the dynamic behavior of flow cracks crossing the mortar-rock interface under impact loading and found that the crack expansion rate of the mortar-granite specimen was about twice as fast as that of the granite specimen, whereas the difference in the rate of the sandstone-mortar specimen was smaller. [PERSON], [PERSON] [19] built an empirical formula for calculating the shear strength of binary interfaces based on indoor experiments using a discrete element numerical simulation method for shear tests of binary interfaces with different roughness. Using FLAC\({}^{\text{3D}}\), [PERSON] and [PERSON] [20] found that the shear strength, residual strength, peak strength displacement and strain softening degree of sawtooth rock-mortar interfaces were closely related to the internal friction angle of mortar. From the perspective of microscopic parameters, the influence of the parallel bond modulus ratio on the failure mode and failure development of binary interfaces was subsequently explored [21].