Paper Title
Effect of Transverse Isotropy on Tensile Strength and Deformability of Phu Phan Sandstone

The objective of this study is to investigate the effect of transverse isotropy on tensile strength and elastic parameters of Phu Phan sandstone. Brazilian tension tests are performed on disk specimens with 74 mm in nominal diameters and 37 mm in lengths. The results indicate that the tensile strengths are largest when bedding planes are normal to diameter loading. They decrease to the smallest value when the beds are parallel to the load direction. The tensile elastic moduli are lower than the compressive elastic moduli. This is because the effort required to dilate the pore spaces and fissures in the rocks under compressive loading is higher than that to contract them under tensile loading. The Poisson’s ratio varies with bedding orientation. The Poisson’s ratio under uniaxial and biaxial stresses state are virtually identical. The findings obtained here can be used to assess the stability of tunnel and underground excavation in the sandstone. Keywords - Bedding plane, Sandstone, Brazilian tension test, Elastic parameters.