Comparison of dynamic and static properties of sandstone and estimation of shear wave velocity and Poisson's ratio

Geomechanical properties of rocks are the basic requirements for the construction of civil structures. In the present study, a new relationship between static elastic modulus (Es) and dynamic elastic modulus (Ed) was developed. Also, shear wave velocity (Vs) and static Poisson's ratio (SPR) were estimated based on index tests using support vector regression (SVR), artificial neural network (ANN), simple regression (SR) and multivariate regression (MVR). For this purpose, petrographic, physical, mechanical and dynamic experiments were performed on 54 core specimens. The results obtained from the samples in XRD and thin sections showed that they are mineralogically composed of quartz, feldspar, dolomite and calcite minerals. The samples were classified as feldspathic litharenite. With increase in the amount of quartz in samples, uniaxial compressive strength, compressional and shear wave velocity and Es increased. The results showed that the Ed/Es ratio was 2.45 and the dynamic Poisson's ratio to static Poisson's ratio was 1.99. The most accurate correlation between Ed and Es is a linear equation with a correlation coefficient of 0.78. The Levenberg-Marquardt training law showed the best performance in predicting Vs and SPR. Also, the ANN, SVR and MVR methods are conservative in estimating these characteristics. Comparison of performance of the methods in estimating Vs and SPR showed that SVR has higher accuracy than SR, MVR and ANN.