Abstract: With the paucity of research on rockburst monitoring，the uniaxial compression test of the rockburst of complete hard rock was carried out with whole-course ultrasonic monitoring. On this basis，failure characteristics and ultrasonic precursor law of rockburst was analyzed and the forecast of rockburst was discussed. The results have shown that the crackling sound produces when the load reaches its peak intensity and then rockburst of complete hard rock occurs. The analysis of sample debris helps find evident splitting phenomenon in the outer region and more serious powder degree of fracture surface and shear phenomenon close to the interior of the specimen, which was the consequence of the strong friction and high energy consumption caused by the increase of internal constraint degree. According to the whole-course ultrasonic monitoring of the rockburst of the complete hard rock, wave velocity develops from stability to fluctuations with the first wave amplitude fluctuating from slightly to violently and the attenuation coefficient from increasing to declining, which can be used as the precursor of rockburst; the first wave amplitude changing from the overall decreasing to significantly increaseing or from continuous decreasing to small fluctuations can also be used as the precursor of rockburst; besides, the process of hard rock specimens rockburst from deformation to damage and fracture and finally burst under load can be reflected by hard rock ultrasonic spectrum.

Key words: rockburst, ultrasonic monitoring, complete hard rock, uniaxial compression test, precursor, attenuation coefficient