Paper Title
Effect of Transverse Isotropy on Tensile Strength and Elastic properties of Phu Phan Sandstone by Four-point Bending Test

Four-point bending tests have been performed on prismatic block specimens of bedded sandstone under various bedding plane orientations. Rock specimens are prepared from Phu Phan formation to obtain nominal dimensions of 30×30×200 mm3. Bedding orientations (β) are separated into two cases; 1) beds are parallel to main axis, and 2) beds are normal to main axis. The results indicate that the transverse isotropic effect under tension occurs where tensile strength is lowest when normal to bedding planes makes an angle of 90 with loading direction and they gradually increase to the highest when β = 0. The elastic moduli and Poisson’s ratios under tension are lower than those under compression. The elastic parameters are compared with those obtained from Amadei’s solution. The findings can be used to predict tensile strength of sandstone under various bedding orientations and to design the maximum unsupported roof span of underground opening. Keywords - Bedding Plane, Four-Bending Test, Elastic Modulus, Poisson’s Ratio.