Keywords: 
• shale /
• bedding inclinations /
• failure mode /
• brittleness index /
• discrete element simulation

Abstract: Based on experimental results of shale specimens under triaxial compression, PFC2D was used to simulate the mechanical properties of shale with different bedding inclinations under triaxial compression. The influence of bedding inclinations and confining pressure on shale mechanical properties is analyzed. The results reveal that: (1) With the increase of bedding inclination, the peak strength and cohesion of shale all display "U"-type variation, but the trend of peak strength is different under different confining pressures; the internal friction angle varied nonlinearly with the bedding inclination increases. (2) The failure modes of shale with different bedding inclinations are different. Specimens with β=30°~45° are prone to shear failure along the bedding, while Specimens with β=0°~15° and β=60°~90° are prone to conjugate shear failure. (3) At the same bedding inclination, the number of microcracks at the final failure of the specimen increases with the increases of confining pressure. Under the same confining pressure, the number of microcracks in the final failure of the specimen decreases first and then increases with the increases of bedding inclination. (4) With the increases of confining pressure, the brittleness of shale with the same bedding angle decreases as a whole. Under low confining pressure, shale brittleness is larger at both ends and smaller in the middle with the increase of bedding inclinations.