ABSTRACT
ABSTRACT: Seismic wave velocities as well as the three principal strains were measured in the rectangular prisms of Westerly granite under three different intermediate principal stresses. Compression wave velocities for the three principal stress directions and two polarized shear wave velocities for the minimum principal stress direction were measured during axial loading. The compression wave velocity anisotropy between the intermediate and minimum principal stress direction increased with the increment of the intermediate principal stress. The decrease in the velocity of the two polarized shear waves in the minimum principal stress direction showed a considerable difference in the confining pressure experiment, while it became almost equal under the higher intermediate principal stress state. Using the relation between velocities and crack densities, the crack densities and average aspect ratios were calculated for the two types of flat spheroidal cracks whose planes are perpendicular to the intermediate and the minimum principal stress directions.
