Anisotropy in ultrasonic pulse velocity and dynamic elastic constants of laminated sandstone

Some rocks of the crust, such as sandstones, contain fabric elements including lamination. In general, these rocks show anisotropic behaviour. In this study, anisotropic behaviour of ultrasonic pulse velocities (V-p and V-s) and dynamic elastic constants (elastic modulus (E) and Poisson's ratio (nu)) were investigated for a laminated sandstone. For this purpose, some cylindrical specimens of the sandstone were prepared at angles (beta) of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees to lamination direction. The V-p, V-s, E and nu were measured for the specimens for the different beta values. The study confirms that anisotropy is one of the most important factors affecting V-, V-s, E and nu. The obtained results reveal that V-p, V-s and E show a decreasing trend with an increase in beta from 0 degrees to 90 degrees; whereas nu shows an increasing trend. According to the values of maximum and minimum V-p, V-s, E and nu for different beta values, anisotropy ratios for sandstone samples are 1.16, 1.26, 1.52 and 1.15, respectively. Finally, it can be concluded that calculated V-p, V-s, E and nu corresponding to different beta values are useful for the analysis and design of geotechnical projects in the absence of borehole explorations.