A new approach to the evaluation of rock mass rupture and brittleness under triaxial stress condition

It is significant to accurately evaluate the brittleness of rock mass for the effective evaluation post-fracture of unconventional oil and gas reservoirs and stability of underground mining engineering. The failure of rock mass under compression is regarded as deformation and rupture of the double-body system. A new index for the brittleness evaluation of rock mass is proposed based on catastrophe theory. The new method can provide critical detail description to the variation of critical rupture point, catastrophe energy, post-peak external work, and brittleness index of rock mass under different confining pressures. Red sandstone and granite specimens were selected for compression tests under different confining pressures. The results showed that released kinetic energy, strain of the critical rupture position, and external work varied linearly, approximately, while softening modulus and brittleness index varied polynomially, as confining pressure increased. The results are reliable and reasonable when the rock is regarded as double-body system to study the rupture and brittleness characteristics. The findings of this paper can mitigate some of limitations in existing research.