加载速率效应对花岗岩破裂的力学性能及能量转化机制的影响

基于单轴压缩下的花岗岩破坏试验,结合岩石破坏过程中的能量转化机制,对不同加载速率下花岗岩损伤变形的力学参数、能量转化机制进行了探讨。研究表明,随加载速率的提高,花岗岩的峰值应力、起裂应力逐渐增大,峰值应变、起裂应变逐渐降低,但起裂应变与峰值应变之比却呈现先减小后增大的趋势;随着加载速率的提高,花岗岩试件的峰前总吸收能U^0、可释放应变能U^1、耗散应变能U^2均逐渐增大;当加载速率较低时,花岗岩试件沿最大主应力方向实现劈裂、张拉破坏,此时宏观破坏裂纹较少;而当加载速率较高时,岩石试件由多条裂纹贯通破坏,其破坏形式属于劈裂裂纹与剪切裂纹共同主导的混合破坏模式。

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 U^0,releasable strain energy U^1 and dissipative strain energy U^2 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.