The direct shear test is the most widely used test to study the shear behavior of the concrete-rock interfaces, though the preparation of the sample and the normal stress configuration can affect the results of the tests. The cleanliness of the rock surface before concrete casting influences the strength of the concrete-rock bonds [35]. The formulation and/or the casting procedure of concrete can result in the shrinkage of concrete at the concrete-rock interfaces [35; 36]. This shrinkage generates partially bonded concrete-rock interfaces which influence the shear behavior. The direct shear test is usually performed using the configuration of constant normal loading (CNL) or constant normal stiffness (CNS). The main difference between these two conditions is that direct shear tests conducted under the CNL condition show more dilation in comparison to the direct shear tests performed under the CNS condition, which leads to lower peak shear strength of the interfaces [37]. Recent experimental works outline that the shear behavior of the bonded concrete-rock interfaces under low normal loading depends principally on the condition of the interface, the combination of the stress state, and the configuration of the test. For the influence of the condition of the interface, the most important parameters are the roughness of the interface and the strength of the concrete-rock bonds [6; 38; 39; 40]. For the stress state and the configuration of the test, the most influencing parameters are the scale of the samples and the boundary conditions of the test [37; 41]. Out of all these parameters, the surface roughness and the strength of concrete-rock bonds appear to play an important role in the shear behavior of bonded concrete-rock interfaces. Moreover, their complex relationship still needs more investigation to be fully understood. The results of such an investigation are presented in the first part of this paper. The experimental investigation of the shear behavior of concrete-rock interfaces raised many questions; to better understand this behavior, it is important to develop numerical modeling. A small yet growing body of works of literature on this topic have been published. For example, [PERSON] et al. [39] and [PERSON] et al. [42] used a cohesive frictional model to simulate the direct shear test of relatively smooth concrete rock interfaces, respectively, concrete-limestone interfaces (\(JRC\leq 2\)) and foamed concrete-sandstone (\(JRC\leq 3\)), with a special focus on the bond strength. [PERSON] et al. [43] used the discrete element method to simulate the direct shear test of unbonded concrete-rock interfaces. [PERSON] et al. [44] used finite element modeling to conduct 3D simulations of direct shear tests of unbonded and naturally rough concrete-rock interfaces with an explicit representation of the topography of the interface. [PERSON] et al. [45] presented a 3D numerical modeling that captures the behavior of rock bolts and shotcrete-rock interfaces. [PERSON] et al. [46] proposed a softening constitutive law for concrete-rock interfaces and investigated the crack propagation along with this interface. Despite this progress, there is still little research that has focused on the numerical modeling of the naturally rough and bonded concrete-rock interface under a relatively low normal stress.