关键词: 加载速度, 剪切带, 轴向应力, 侧向应变, 体积应变, 泊松比

Abstract: FISH functions written are used to calculate axial, lateral and volumetric strains as well as Poisson’s ratio of rock specimen in plane strain compression. Influence of loading rate on shear band (SB) pattern and entire deformational characteristics is investigated numerically using FLAC. In elastic and strain-softening stages, the constitutive relations are linear. A composite Mohr-Coulomb criterion with tension cut-off is used. For lower and moderate loading rates, a SB whose inclination angle and thickness are not influenced by loading rate bisects the specimen, so that the post-peak slopes of stress-axial strain curve and stress-lateral strain curve are not related to loading rate. Higher loading rate leads to the conjugate SBs, resulting in less steep post-peak stress-axial strain curve and stress-lateral strain curve. At the same axial strain, higher loading rate leads to shorter SB. With an increase of loading rate, the precursor to failure is more apparent unless the loading rate is very high. At higher loading rate, the great fluctuation in stress exists so that the axial strain corresponding to the peak stress is estimated inappropriately. In strain-softening stage, higher loading rate results in ductile lateral strain-axial strain curve, Poisson’s ratio-axial strain curve and volumetric strain-axial strain curve as well as higher peak of volumetric strain and the corresponding axial strain.

Key words: loading rate, shear band, axial stress, lateral strain, volumetric strain, Poisson’s ratio