THE ULTRASONIC IDENTIFICATION OF ROCK MASS CLASSIFICATION AND ROCK MASS STRENGTH PREDICTION

Rock mass classification and rock strength predication are widely applied in rock engineering. In this paper several classifications have been developed for rock mass, e.g. the RMR and Q-system, and the Hoek-Brown criteria is the most accepted for rock mass strength predication. A combination of the RMR and Q-system is related to ultrasonic velocity based on the foregoing investigations and experience formulae, so that the rock mass classification can be assessed according to the measured ultrasonic velocity of rock mass in situ. Also by the existed relationship between the RMR and Hoek-Brown criteria, a prediction for the strength parameters of rock mass is reached. An example taken from the Three Gorges Project of Yantze River has shown the application significance in rock engineering.