Influences of loading rate on the stress level when a system composed of fault band and elastic rock was formed

the size of plastic zones

the patterns of localized shear band

the maximum load-carrying capability of the system

and on the stress level when the snap-back of the system occurred were modeled numerically by FLAC (Fast Lagrangian Analysis of Continua). The adopted failure criterion was a composite Mohr-Coulomb criterion with tension cut-off; and a linear strain-softening post-peak constitutive relation of rock was adopted. In general

after fault band-elastic body system is generated

the load-carrying capability of the system reaches its maximum value. Thereafter

it begins to decrease so that the system is in strain-softening stage. If the post-peak stiffness of compressive stress-compressive displacement curve for the monitored element at loading end of plane strain specimen is high enough

the snap-back (unstable failure) of the system occurs. As loading rate increases

the stress level corresponding to the formation of the system and the corresponding displacement increase; the maximum load-carrying capability of the system and the corresponding displacement increase; the stress level when the snap-back of the system occurs and the corresponding displacement increase. As loading rate increases

the number of yielded elements increases and the thickness of fault band no loner remains a constant

leading to an increase in deformation resistant of the system. For higher loading rate

it is possible that higher shear strain rates are concentrated into both fault band and some elements remaining elastic outside the band.