为探究反复冷却处理后花岗岩的声发射特征及破坏机制,使用岛津力学试验设备、声发射监测及扫描电子显微镜系统对不同温降等级、冷却循环次数等影响因素处理下的花岗岩试件进行单轴压缩力学试验研究。结果表明:经温降等级10、15和20℃处理后的花岗岩峰值应力分别降低了28.6%、12.9%和6.8%,温降等级越小,峰值应力降低幅值越大。不同冷却处理方式下的花岗岩声发射振铃计数均可划分为平静期和活跃期两个阶段,并随温降等级降低或冷却循环次数增加,花岗岩结构损伤加剧,平静期持续时间延长。花岗岩破坏模式受温降等级和冷却循环次数影响,温降等级10℃时以张拉破坏为主;温降等级15℃时,破坏模式随循环次数增加逐渐由拉剪混合破坏向张拉破坏转变;温降等级20℃时以拉剪混合破坏模式为主。

To investigate the acoustic emission characteristics and failure mechanism of granite after repeated cooling treatment, uniaxial compression mechanical tests were conducted on granite specimens treated with different temperature drop levels, cooling cycles, and other influencing factors by using Shimadzu mechanical testing equipment, acoustic emission monitoring, and scanning electron microscopy systems. The experimental results show that the peak stress of granite treated by temperature drop levels of 10, and ℃ decreased by 28.6%, 12.9%, and 6.8% respectively. The smaller the temperature drop level is, the greater the amplitude of peak stress reduction becomes. The acoustic emission ringing counts of granite under different cooling treatments can be divided into two stages: The calm period and the active period. As the temperature drop level decreases or the cooling frequency increases, the damage to the granite structure intensifies and the duration of the calm period extends. The failure mode of granite is influenced by the temperature drop level and cooling frequency. At a temperature drop of ℃, tensile failure is the main mode. At a temperature drop of ℃, the failure mode gradually changes from tensile shear mixed failure to tensile failure with increasing cycles. At a temperature drop of ℃, tensile shear mixed failure mode is the main mode.