The effects of weak interlayers on the dynamic mechanical properties and failure behaviours of rocks: A combined numerical and experimental analysis

Rock strata often contain weak interlayers, and it is vital to understand how rocks respond to dynamic loads for predicting natural disasters such as earthquakes and landslides. In this paper, a combined numerical and experimental analysis is carried out to investigate the dynamic properties and failure behaviours of specimens with and without a weak interlayer. Specifically, split Hopkinson pressure bar tests are employed, and numerical simulations of these tests are developed in the framework of the extended finite element method. Additionally, the feasibility of the proposed numerical method for modelling the split Hopkinson pressure bar is verified by comparison with laboratory tests. The results demonstrate that the existence of a material interface or a weak interlayer in the specimen can cause stress concentrations under dynamic stress waves and that the failure be-haviours of the specimen can also be changed. Evidently, the failure pattern in the intact specimen consists of a compression-shear failure pattern and a tensile failure pattern. The failure pattern in the specimen containing a persistent flaw is the compression-shear failure pattern, and the failure pattern in the specimen containing a weak interlayer consists of a compression-shear failure pattern and a tensile failure pattern, in which the number of tensile cracks increases with increasing thickness of weak interlayers in the specimen.