Fig 1.
Preparation process of phyllite specimens (a) Core drilling, stone cutting, and grinding process (b) Final prepared standard cylindrical specimens (φ50 mm×100 mm) with different bedding angles (c) Schematic diagram of phyllite specimens with different bedding angles.
Fig 2.
Experimental apparatus: (a) Electronic scale (b) Vernier caliper (c) ZBL-U520 non-metallic ultrasonic detector (d) ROCK 600−50 rock full-stress multi-field coupling triaxial testing apparatus ① Main system control display panel ② Data acquisition system ③ System valve operation panel ④ Axial pressure system ⑤ Triaxial pressure chamber.
Fig 3.
SEM images of phyllite specimens.
(a) 2000× (b) 5000×.
Fig 4.
Longitudinal wave velocity characteristics of phyllite specimens at different bedding angles.
Fig 5.
Stress-strain output of triaxial compression tests carried out of layered phyllite at a confining pressure of 10 MPa (a) ε1 VS σ1-σ3, ε3 VS σ1-σ3 (b) εv VS σ1-σ3.
Fig 6.
Stress-strain output of triaxial compression tests carried out of layered phyllite at a confining pressure of 20 MPa (a) ε1 VS σ1-σ3, ε3 VS σ1-σ3 (b) εv VS σ1-σ3.
Fig 7.
Stress-strain output of triaxial compression tests carried out of layered phyllite at a confining pressure of 30 MPa (a) ε1 VS σ1-σ3, ε3 VS σ1-σ3 (b) εv VS σ1-σ3.
Fig 8.
Shows the relationship between peak strength and bedding angle, as well as confining pressure for the phyllite specimens.
(a) The effect of bedding angle (b) The combined effect of bedding angle and confining pressure.
Fig 9.
Shows the relationship between the elastic modulus and bedding angle, as well as confining pressure for the phyllite specimens.
(a) The effect of bedding angle (b) The combined effect of bedding angle and confining pressure.
Fig 10.
Variation of Poisson’s ratio of phyllite specimens with bedding angle and confining pressure: (a) Effect of bedding angle (b) Effect of confining pressure.
Fig 11.
Curves of internal friction angle and cohesion of phyllite specimens at different bedding angles.
Fig 12.
Failure modes of typical phyllite specimens under different bedding angles and confining pressures.
(a) 10 MPa, (b) 20 MPa, (c) 30 MPa.
Fig 13.
Strain energy and axial strain relationship curves of phyllite specimens with different bedding angles under 10 MPa confining pressure (a) β = 0°(b) β = 30°(c) β = 45°(d) β = 60°(e) β = 90°.
Fig 14.
Strain energy and axial strain relationship curves of phyllite specimens with different bedding angles under 20 MPa confining pressure (a) β = 0°(b) β = 30°(c) β = 45°(d) β = 60°(e) β = 90°.
Fig 15.
Strain energy and axial strain relationship curves of phyllite specimens with different bedding angles under 30 MPa confining pressure β = 0°(b) β = 30°(c) β = 45°(d) β = 60°(e) β = 90°.
Fig 16.
Variation of strain energy at peak stress point with layering angle and confining pressure.
(a) total strain energy, (b) elastic energy, (c) dissipated energy.