Influence of Layer Thickness Ratio on the Mechanical and Failure Properties of Soft-Hard Interbedded Rock-like Material

To figure out the influence of soft-hard layer thickness ratio on specimens’ mechanical properties evolution and microcracking mechanism, combined with digital image correlation technology and acoustic emission facility, uniaxial compression tests were conducted on soft-hard interbedded rock-like materials considering seven bedding dip angles and two soft-hard layer thickness ratios. The results are as follows: 1) The failure mode and failure pattern of layered rock masses are mainly determined by the bedding dip angle α and are less related to the soft-hard thickness ratio. With the increase of dip angle, the failure strength curve of the specimen is approximately U-shaped, and the soft-hard layer thickness ratio affects the U-shaped. The decrease in soft-hard layer thickness ratio will reduce the uniaxial compressive strength of specimens with low dip angles (α≦30°), cause differences in the evolution path of local strain fields of layered rock masses and reduce the horizontal displacement of the main crack. 2) The increase of the proportion of soft layer in the soft-hard layer thickness ratio will reduce the proportion of tensile cracks in the tensile failure specimens and shear cracks in the shear failure specimens, complicating the process of cracks of the layer rock mass. 3) Increasing the proportion of soft layers in the soft-hard layers thickness ratio promotes the generation of secondary cracks in layered rock masses and further reduces the integrity of specimens. Finally, through the findings in this paper, it can provide a reference for analyzing the crack propagation behavior of layered rock.