Prediction of mechanical and physical properties of some sedimentary rocks from ultrasonic velocities.

In this study, density, porosity, void ratio, and ultrasonic P- and S-wave first arrival times were measured on limestone, sandstone, and siltstone samples obtained by using mechanical soundings in the city of Zonguldak. Turkey. Fracture and fissure indexes of rocks were calculated from ultrasonic P- (Vp) and S-wave (Vs) velocities. Multi-parameter relationships occurred between ultrasonic velocities with seismic fracture and fissure indexes and physical and mechanical properties of the rocks. Root mean squared error (RMSE = 0.5–0.8%) values correlated between measured densities and densities calculated from Vp and Vs. The correlation coefficients of experimental relations between densities, void ratio, and porosity with seismic velocities that were obtained ranged from 78, 86, 67, and 84%, respectively. Consequently, natural, water-saturated and grain densities, porosity, and void ratio values were determined from new multi-parameter relationships obtained from the combined use of Vp and Vs. In addition, the results of this study suggest that the rock quality may wrongly be determined using the only Vp, whereas it can be obtained more accurately by using Vp and Vs together. The reason for this is that the P wave spreads in solid, liquid, and gas media, while the S-wave spreads only in solid media. Therefore, S-waves will not be altered by fracture filling (gas or liquid), while P-waves are affected by fracture filling. In the present study, the use of Vp and Vs together in relationships was more useful in determining the strength and hydraulic properties of rock mass that the use of either Vp or Vs alone. Also, Rock Quality Designation (RQD) and Rock Mass Rating (RMR) values can be correctly calculated from the combined use of Vp and Vs. As a result, interpretation of crack fill and classification of the rocks can be quickly performed using seismic velocities. [ABSTRACT FROM AUTHOR]