Rock burst is one of the major disasters in deep mining and it appears that the frequency and intensity of rock burst will increase with the buried depth of rock engineering. Burst tendency is the inherent factor that determines whether rock burst occurs or not. We put forward a new rock burst tendency index—Yield Degree using the stress-strain curves of rock specimens under the conditions of uniaxial and triaxial compression. All in all, rock burst tendency is bigger when YD is smaller. Then we respectively analyzed rock burst tendency under different conditions which are submergence, confining pressure, and ratio of height to diameter. The results show that YD becomes bigger when the specimens have been submerged in water, increases with the increase of confining pressure, and decreases with the increase of the ratio of height to diameter of the specimens. Above conclusions could provide a certain thought to control rock burst for rock engineering.
Rock burst is one of the major disasters which occur in underground engineering frequently. According to the theory of rock burst mechanism, the occurrence of rock burst is concerned with its own properties, the magnitude of stress that rock bears and the energy storage and release of rock. The breed and occurrence of rock burst include the physical process of loading on rock mass, energy storage, energy dissipation and sudden deformation failure with instantaneous release of large amounts of energy, and its performance is transformation of energy's basic form. Rock burst tendency of rock mass is the necessary condition when stain-type rock burst occurs, and it is the important issue of studying on rock burst and is the foundation of rock burst forecast and prevention control (Chen, S. J. et al. 2007, Zhang, X.Y. et al. 2007).At present, scholars have put forward various rock burst indexes, such as elastic energy index, impact energy index, the maximum plastic deformation velocity and brittleness index etc (Pan, Y. S. et al. 2010). Elastic energy index reflects the energy storage ability in prepeak phase of the uniaxial compression stress-strain curve of rock specimen. Impact energy index considers the relationship between energy storage in pre-peak phase and energy dissipation in post-peak phase (Tang, L. Z. &Wang,W. X. 2002). However, these rock burst indexes have some shortcomings. For example, elastic energy index cannot research post-peak energy dissipation. And impact energy index cannot consider the actual energy accumulation value in pre-peak loading phase (Zhu, F. C. et al. 2002). What's more, it is difficult to determine the stress level to confirm elastic energy index, and it is difficult to determine the origin of residual stress phase to confirm impact energy index. The brittleness index emendation value (BIM) which can escape these shortcomings was put forward (Aubertin, M. et al. 1994). Otherwise, Plastic deformation energy is dissipated energy with plastic deformation of rock specimen. As we know that plastic deformation energy can't release and only pre-peak elastic energy can release in post-peak phase because plastic deformation can't be recovered, so that prepeak yield has close contact with plastic deformation. Therefore, a new rock burst tendency index and rock burst tendency evaluation method were put forward after studied the characteristic of pre-peak yield phase and its relationship with BIM (Chen,Y. & Guo, B. H. 2013).
