关键词: 岩石试样, 光滑粒子流体动力学, 单轴压缩, 剪切带, 声发射, 应力跌落

Abstract: Using the self-developed code based on the SPH (smoothed particle hydrodynamics) method, evolution of the shear bands and acoustic emission events during failure processes of heterogeneous rock specimens under plane strain uniaxial compression is studied. Based on the Mohr-Coulomb criterion with tensile truncation, the stress calculation method of the failed particle is deduced under the assumption that the spherical stress tensor is invariant during the stress drop. Numerical results show that the longitudinal stress-longitudinal strain curves of the specimens with lower homogeneous degrees demonstrate obvious strain hardening and strain softening stages; strain hardening stages of the specimens with higher homogeneous degrees become less obvious with an increase of the homogeneous degree, and post-peak behaviors of specimens are obviously brittle. Stress drops of particles with different cohesions are theoretically analyzed. Results show that stress drops of particles with higher cohesions are not necessarily larger than the particles with lower cohesions. Stress drops are not only related to the cohesions of the particles, but also to the stress states of the particles when they fail. Effects of homogeneous degree on distributions of failed particles are qualitatively analyzed. The analysis shows that as the homogeneous degree increases, failed particles are more likely to form a narrow shear band quickly penetrating the specimen, with almost no particles failed outside the shear band once the specimen is penetrated. Therefore, the number of final failed particles in the specimen is fewer with an increase of the homogeneous degree.

Key words: rock specimen, smoothed particle hydrodynamics (SPH), uniaxial compression, shear band, acoustic emission, stress drop