Prediction of rock burst potential by analysis of ultrasonic velocity data

In this paper, a quantificational formula between ultrasonic velocity through rock specimens with different burst potential and their axial strain is presented, and it is proved reliable based on the test results of three different kinds of rock specimens under uniaxial compression. The results show that when rock burst potential is strong, the ultrasonic velocity changes little as the strain increases in forepart of loading, and declines suddenly at a definite load. While rock burst potential is weak, the ultrasonic velocity declines gradually. A new conception called reduction-factor of ultrasonic velocity is brought forward to inverse the rock burst potential, and the classification criterion is suggested. As the survey of ultrasonic velocity through rock mass is easy correspondingly in rock engineering, these rules lead a new way to predict and evaluate rock burst risk.