Abstract:
This paper presents the numerical investigation results of failure process, failure modes and strength anisotropy of layered rock under a series of uniaxial compression and Brazilian tests. This paper employs 2-D Particle Flow Code (PFC) to simulate layered rock models for different inclination angles(?) that varies from 0° (the layer is perpendicular to the loading direction) to 90° (the layer is parallel to the loading direction). Based on the numerical simulation results, the uniaxial compressive strength decreases with the increase of the inclination angle at 0° ≤? ° then the uniaxial compressive strength slightly increases at 60° ≤? °. Three kinds of failure modes under uniaxial compression test could be observed: (a) Sliding failure across layers mode, (b) Sliding failure along layer mode, and (c) Tensile split along layer mode. The inclination angle has a more significant effect on the tensile behavior of layered rock under Brazilian test. The tensile strength of layered rock decreases with the increase of the inclination angle. Through the numerical investigation of failure process during Brazilian test, the micro-cracks roughly initiate at 50% of ultimate stress near the contact boundary then propagate slowly until the peak is reached. After the ultimate stress is reached, the mico-cracks start to form macro-cracks and the failure of layered rock under Brazilian test can classified into four modes: (a) Split across layer mode: the cracks propagate across layers at 0° ≤? °, (b) Sliding along layer mode: the cracks slide along the layer at 45° ≤? °, (c) Mixed mode: both split across layer and sliding along layer mode could be observed at ?=75°, and (d) Split along layer mode: the cracks propagate along layers at ?=90°. Furthermore, the numerical simulation results compare with the experimental data from Cho et al. (2012). Although the failure modes under Brazilian test at 45° ≤? ° are a little difference, the uniaxial compressive strength, failure modes under uniaxial compression test, and tensile strength agree well with the experimental data from Cho et al. (2012).