Effect of Transverse Isotropy on Tensile Strength And Elastic Modulus of Phu Phan Sandstone
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Abstract
This research aims to investigate the effects of transverse isotropy on tensile strength and elastic modulus of Phu Phan sandstone. The dimensions of disk-shaped specimens were 74 mm diameter and 37 mm thickness. Brazilian tension tests were performed under two stress states: 1) under uniaxial stress direction with bedding planes normal and parallel to core axis and 2) under biaxial stress state with bedding planes parallel to the core axis. The test results indicate that strengths are largest when bedding planes are normal to loading diameter. They gradually decrease to the smallest value when the beds are parallel to the loading 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 under uniaxial stress direction decreases with increasing inclination angles. The findings obtained here can be used to assess the stability of sandstone tunnels and underground excavations.
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