Abstract: According to the characteristic of elastic waves propagation in medium and the application of elastic wave method in rock mass engineering, the paper has analyzed the characteristic of elastic waves propagation in cracked rock masses. It has put out the relationship of effective dynamic parameters of elasticity ( , , ) and crack density parameters, according to the principle of energy balance, rock rupture mechanics and Castiglano’s theorem, by looking the cracked mass with random cracks as quasi-isotropic cracked mass. On this basis, and through the theory of elastic wave propagation in isotropic medium, it has made out the relationship between the elastic wave velocity and crack density parameters. The theoretical research has shown that, in this kind of cracked rock masses, it will be nonlinear relationships between the effective dynamic parameters of elasticity and wave velocities and the crack density parameter; and with the increase of crack density parameter, the effective dynamic modulus of elasticity and the elastic wave velocities decrease; and at the same time, when the crack density parameter is very small, the effective dynamic modulus of elasticity and the elastic wave velocities change with the crack density parameter much more, which has explained the sensitivity of effective elastic parameters and elastic wave velocities to cracked rock masses.

Key words: quasi-isotropic cracked mass, wave velocities, effective dynamic parameter, crack density parameter