Anisotropy of Mechanical Properties in Kimachi Sandstone, Japan

We carried out P wave velocity tests and uniaxial compression tests in various directions to investigate the anisotropy of mechanical properties of sedimentary rock. First of all, two plate shaped blocks were prepared which are vertical and parallel to the bedding plane. Twelve cylindrical specimens were prepared for each block in different directions (every 30 degree, size: f 50 mm, h 100 mm). Elastic wave velocities and uniaxial compression strength were carefully measured. The anisotropies of P wave velocity were insignificant for both blocks. However, anisotropy of uniaxial compression strength was noticeably high on the horizontal block. The changes of Young's modulus anisotropies on both block specimens were also investigated for different stress levels (10, 30%, 50%, 70% and 90% of uniaxial compression strength). The experimental results indicate that the anisotropy of mechanical properties in Kimachi sandstone is strongly related with the sedimentation environment. However, the directions of bedding plane and cross-lamination were not influential to the anisotropy of mechanical properties.