Research on acoustic emission characteristics and failure mechanism of granite treated by repeated cooling
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 10,15 and 20℃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 10℃,tensile failure is the main mode.At a temperature drop of 15℃,the failure mode gradually changes from tensile shear mixed failure to tensile failure with increasing cycles.At a temperature drop of 20℃,tensile shear mixed failure mode is the main mode.
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