Effect of Loading Rate on Mechanical Properties and Energy Conversion Mechanism of Granite Fracture

Based on the failure test of granite under uniaxial compression and the mechanism of energy transformation in the process of rock failure, the mechanical parameters and energy transformation mechanism of granite damage and deformation under different loading rates were discussed. The results show that with the increase of loading rate, the peak stress and initial crack stress of granite gradually increase, and the peak strain and initial crack strain decrease gradually, but the ratio of initial crack strain to peak strain decreases first and then increases. With the increase of loading rate, the total pre-peak absorption energy U⁰, releasable strain energy U¹ and dissipative strain energy U² increase gradually. When the loading rate is low, the granite specimen is split and tensioned along the direction of the maximum principal stress, and the macroscopic fracture crack is less. When the loading rate is high, the rock specimen is broken by multiple cracks, which belongs to the mixed failure mode of split crack and shear crack.