Damage mechanism and stress wave spectral characteristics of rock under tension

The tensile property of rock is much worse than its compression performance, and the damage mechanism under tension determines the stability and safety of rock engineering. To study the tensile damage mechanism of rock, the vibration theory and acoustic emission (AE) signal tests under indirect tensile conditions are used to analyze the damage evolution process of granite. The tensile damage mechanism is obtained by using the fractal theory and the distribution of dominant frequencies and energies of AE signals. Based on the distribution of AE events, damage is instantaneous and the number of AE events sharply increases when the loading stress reaches its ultimate tensile strength (UTS), reflecting apparently brittle performance. The fractal dimension of AE events decreases as the loading stress increases. The dominant frequencies of AE signals at the indirect tensile stage are mainly concentrated at 175~250 kHz and 50~100 kHz. Their energies are intensively distributed in the band width of 0~312.5KHz. The stress wave characteristics and fractal mechanism can reflect the basic mechanical property of rock. They are of important experimental and theoretical significance for further studies on rock performance and enhancing the safety of rock engineering.