Fracturing evolution and strain characteristics of layered rock-like materials with rough interfaces

Abstract

Layered rock-like samples containing saw-tooth interfaces of various joint roughness coefficients (JRC) and included angles were conducted uniaxial compression with the loading rate of 0.005 mm/s. The peak stress declines from 38.36–39.90 MPa to 17.35–30.67 MPa for included angle = 15°–60°, and then increases to 24.30–33.83 MPa for 60°–75°, but the peak strain decreases by 22.39%–41.30%. For JRC = 0–19.55, mechanical properties of samples are enhanced, while the anisotropy weakens. When the included angle is small (15°, 30°), the layered samples show a typical tensile splitting failure crossing the weak interlayers. For a large included angle of 45°–75°, failure modes are featured by shear sliding along weak interlayers combined with tensile splitting. As JRC increases, fracturing mechanism transition from shear sliding to mixed tension shear failure then to tensile splitting can be identified. With an increase in JRC or included angles, the global lateral strain of samples in plastic deformation stages changes from “sudden increase” to “progressive increase” to “jump increase”. For included angle = 15°, the layered sample produces dramatic lateral local strain at the weak interlayers due to tensile splitting failure. For included angle = 45°, both axial and lateral local strains at the weak interlayers show an obvious increase at the main shear failure surface. For a large included angle of 75°, the lateral local strain remarkably increases at the weak interlayers along with tensile failure of samples.