Abstract: To overcome the shortage of study on fracture evolution and monitoring of rockburst in roadways(tunnels), biaxial compression comparative tests are carried out on rectangular granite samples under the constraint of one side by monitoring the whole process using ultrasonic plane testing method. The method of determination of homogeneity and wave velocity is obtained. The mechanism of rockburst and the regularity of ultrasonic wave waveform are analyzed and discussed. The results show that the hard rock presented obvious layer burst phenomenon and the core of rockburst is located in the inner stress concentration zone before the critical bursting. The evolution process of stratified burst of hard rock can be revealed by means of the waveform of ultrasonic plane testing method; the velocity of ultrasonic wave is decreasing in the process of loading; arrival time of the subsequent wave has not obvious change in the earlier stage and metaphase periods; however, the arrival time of the later period is obviously increasing; and the subsequent wave amplitude is generally decreasing in the loading process; the wave amplitude is increasing before the burst. The application of ultrasonic plane testing method in the field of hard rock monitoring is discussed, stratified burst of hard rock can be predicted based on the variation of waveform and wave velocity and nondestructive monitoring of surrounding rock is realized; the damage evolution process and prediction can be further revealed by the damage variables.

Key words: hard rock, stratified burst, ultrasonic plane testing method, biaxial compression test, wave velocity