The rock-concrete interface is usually considered the weakest structural zone in tunnel lining structures. To study the tensile failure of the rock-concrete interface, the Brazilian splitting tests were carried out on sandstone-concrete Brazilian discs using the digital image correlation (DIC) system. The laboratory tensile strength and failure process are consistent with numerical simulation. Then, the tensile behavior of the interface with different roughness was simulated using MatDEM software. Results show that the tensile strength of rock-concrete disc is insensitive to the sawtooth number. The tensile strength increases with increasing sawtooth angle due to increasing total contact area and interlocking effect. When the sawtooth angle is more than the critical value, the tensile strength increases rapidly due to the formation of the breaking sawtooth.
The roughness of the rock surface resulting from blasting significantly impacts the strength of concrete-rock composite structures. The structure is widely used in tunnel lining (Tang et al. 2016), dam foundation (Milovanovic 1972 and Krounis et al. 2016), and other scenes. There is an increasing need to investigate the failure mechanism and process of this structure. Recently, various researchers have studied the shear strength of concrete-rock interfaces with different roughness and numbers of teeth. Saiang et al. (2005) concluded that the peak shear stress at the interface of concrete-rock composite was composed of bond strength and friction. However, most of concrete-rock interfaces were damaged by tensile force, especially under the influence of blasting during construction. Brazilian splitting test is a common method to assess the tensile of concrete-rock interfaces. Results from this test have demonstrated that the tensile strength is correlated with the angle and shape of the interface. As the angle of the interface increases or its shape changes, distinct failure modes can manifest in the Brazilian disk (Chang et al. 2018 and Qiu et al. 2020).
