| Abstract: | Stability equations for a strain-softening system are derived from expressions describing the energy variation in a variable stiffness stiff testing machine and a brittle rock specimen. A normal strain-softening expression and a shear strain-softening expression are derived to predict the stability of laboratory tests on brittle rocks, which through machine stiffness adjustment, exhibited critical stability in the strain-softening range. From these comparisons it was found that the shear strain-softening model gave consistently good results. The analytical and laboratory modelling indicates that strain-softening in brittle geologic media is closely connected with joints, faults, and interfaces where shear distortions take place. |
