Home – Home – Jornals – Fundamental and applied issues of mining 2020 number 1

A laboratory study was conducted to investigate the effect of bedding angle on strength properties of shale and siltstone samples under shear loading with compression. The selected rocks had significant anisotropy of strength properties when tested for compression and tension. The samples of shale and siltstone were tested under shear loading with compression at various combinations of the orientation of bedding angles Ψ relative to the sample axis and the orientation of angles of shear plane Δ relative to sample bedding. Experimental dependences “ultimate shear stress τ - normal stress s” and adhesion value C ₀ on Ψ and Δ angles are obtained. The study concluded that the ultimate shear strength and adhesion was determined by a combination of angles Ψ and Δ. For samples with a bedding angle of Ψ = 90°, the angle Δ has a much more significant effect on the character of failure than the values of normal stresses. The combined effect of the angle Δ and the values of normal stresses σ on the character of failure is observed for the samples with Ψ = 45°. For samples with the orientation of bedding angles Ψ = 90°, the shear strength does not depend on the angle Δ and is determined only by the value of normal stresses.