Paper Title
Effect of Transverse Isotropy on Mechanical Properties of PHU PHAN Sandstone

Compression tests have been performed on prismatic specimens of sandstone under confining pressures up to 12 MPa. The specimens contain different bedding plane orientations. Results indicate that transverse isotropic effect occurs under all confinements where the strength is lowest when the normal to bedding planes makes an angle () of 75 with the major axis. The lowest modulus is obtained at  = 0, and the highest is at = 90. Confining pressures rapidly increase the elastic and shear moduli normal to bedding planestrike, toward those parallel to the beds. Coulomb criterion is capable of describing the rock compressive strengths where the cohesion is defined as a polynomial function of bedding plane orientations. Keywords - Confining Pressure, Bedding Plane, Coulomb Criterion