Investigation of anisotropic strength and deformation properties of the selected sandstones from tertiary units of the adana basin

Rock anisotropy, may be defined as variation of the physical and mechanical behavior of the rocks with respect to the direction of the fabric such as foliation, stratification or jointing. In this study, the variation of anisotropic strength, static and dynamic properties of 7 laminated sandstone blocks, selected from the Cingöz formation of Tertiary sequence of the Adana Basin were investigated. According to the mineralogical and petrographic assessments, selected sandstones were classified as lithic sandstones representing very fine(block 4), fine (1,2,3 and 4) and medium (6-7) grained sandstones. 310 core samples were prepared with respect to the various lamination surfaces as 0, 30, 45, 60, and 90 degrees. Density, porosity and water absorption ratios were determined from the physical properties. Strength anisotropy characteristics were determined from unconfined compressive and indirect tensile tests. Static and dynamic deformation anisotropy characteristics were determined from elasticity modulus and sonic wave velocity tests, respectively. According to the uniaxial strength test results, the strength anisotropy ratio (Rc: ?cmax/?cmin) values were found between 1.27-2.07 referring to low and medium degree anisotropy. Simple regression relations among the uniaxial compressive strength, static and dynamic elasticity modulus, s and p-wave velocities were obtained depicting high coefficients of correlations varying between 0.83 and 0.98 Besides, the variation of uniaxial compressive strength regarding to the orientation angle and density were assessed based on simple and multiple non-linear regression models where coefficient of correlations were found 0.96 and 0.93, respectively. Keywords: Sandstone, anisotropy, anisotropy ratio, regression, multiple regression.