中文摘要：

利用改进的分离式霍普金森压杆（SHPB）系统,对花岗岩进行多次循环冲击压缩试验,并结合岩石声发射监测研究花岗岩在动态冲击下的累计损伤特性。利用超动态应变仪获取的波形信号分析试样中的纵波通过时间,进而计算岩石的应力波波速,并利用花岗岩应力波波速的变化来表征试样在循环冲击过程中的损伤特性。通过分析试样每次加载过程中的能量变化,发现多次冲击加载过程中的岩石损伤量变化程度与试样在单次加载过程中的吸收能大小有关,试样的吸收能越大,花岗岩冲击后的损伤变化量越大。花岗岩在多次冲击加载过程中的动态抗压强度随着冲击次数的增多而减小,但随加载应变率的增大而增大。基于冲击加载过程中的应力时程曲线及声发射信号特征,发现声发射事件峰值计数随着加载次数的增多而增大,表明花岗岩在多次冲击过程中新生裂纹在逐渐增多,花岗岩在每次加载过程中的声发射事件峰值点位于试样应力峰值点附近,且其在动态冲击下的声发射事件具有突发性,前兆信息不明显的特点。

英文摘要：

Based on improved split Hopkinson pressure bar （SHPB）, repeated cycle impact compression experiment for granite was carried out. Adopting acoustic emission （AE） device, accumulated damage characteristics of granite due to dynamic impact were monitored and studied. Using waveform signals obtained by ultra dynamic strain instrument, the longitudinal wave passing through time in granite specimen can be analyzed, and then the stress wave velocity in granite can be calculated. The damage characteristics of granite specimen in cyclic impact compression process can be characterized by the change of stress velocity. Through analyzing specimen energy variation in each impact loading process, it is found that the damage variation of specimen is related with the energy absorption in each impact loading process. The larger the absorbed energy is, the larger the damage variation after impact loading. In addition, in repeated impact loading process, the dynamic compressive strength of granite decreases with the increase of loading times, but increases with the increase of loading strain rate. Based on the stress-time curves and acoustic emission characteristics in the impact loading process, it is found that acoustic emission peak value count increases with the times of cyclic impact loading, which indicates that newly produced crack in granite increases gradually in impact process, and the damage degree increases with the times of cyclic impacts. Meanwhile, acoustic emission signal peak value location is closely associated with its peak stress, the strongest point of the AE events usually approaches the peak stress of granite specimen, and the acoustic emission occurred suddenly, without obvious precursor.