Investigation of Dip Effect on Uniaxial Compressive Strength of Inclined Rock Sample by Experimental and Theoretical Mod
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ORIGINAL PAPER
Investigation of Dip Effect on Uniaxial Compressive Strength of Inclined Rock Sample by Experimental and Theoretical Models Binyu Luo1 · Yicheng Ye1,2 · Nanyan Hu1,2 · Weiqi Wang1 Received: 18 December 2019 / Accepted: 19 August 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The strength of rock under combined compression and shear loading has been paid more and more attention, but still lacks a theoretical model that incorporates both compression–shear characteristics and influence of dip angle to estimate the strength of the rock. This work is aiming to solve the issue by combining experimental and theoretical methods. First, in the laboratory, 112 rock samples with different sizes were applied to obtain the dip effect characteristics of strength via combined compression–shear tests. The ratio of compression–shear strength to uniaxial compression strength is called the compression–shear coefficient, which is used to characterize the degree of dip effect. Second, according to the compression–shear load characteristics of inclined rock samples, a strength model was established considering both compression–shear characteristics and dip angle by the Mohr–Coulomb failure theory. This strength model is an extension of the Mohr–Coulomb criterion and was verified by experimental data. The verification results are consistent with experimental results. Finally, the mechanism of dip effect on strength was explained from the resistance to the sliding and stress path of the rock sample. The results show that the dip effect is an inevitable strength weakening characteristic of rock materials under combined compression–shear loading. Compared with the vertical rock sample loaded under pure pressure, the resistance to the sliding of inclined rock samples decreases and the stress path is changed, which reduces the ability of the rock sample to resist external loads, resulting in the decrease of strength. Keywords Inclined rock · Uniaxial compressive strength · Dip effect · Combined compression–shear loading List of symbols F Total force applied the rock sample (N) Fn, Fs Axial force and tangential force of the rock sample (N) θ Dip of the rock sample (°) σθ, τθ Axial compressive stress and tangential shear stress of the rock sample (MPa) A Cross-section areas of the rock sample (m2) E, G Elastic modulus and shear modulus of the sample at a given dip angle (MPa)
* Nanyan Hu [email protected] 1
School of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China
Hubei Key Laboratory for Efficient Utilization and Agglomeration of Met Allergic Mineral Resource, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China
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ε, γ Axial compressive strain and tangential shear strain of the sample at a given dip angle, 1 d Displacement between two platens of the WAW-300 (m) w, h Width and height of the sample (m) ν Poisson’s ratio, 1 σp Total load of the rock sample (MPa) σθmax, τθmax Axial maximum compr
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