Some physical properties of sandstones lithified under the influence of differential stresses
University of New Brunswick
The result of two experiments is discussed in this thesis. The first experimental project involved the testing of concrete cubes solidified under the stress conditions of σ1 > σz=σ3 where σ1 was the experimental variable. Pulse velocity anisotropy occurred with the slower velocity in the 01 direction and the two faster (and equal) velocities corresponding to the σ z and σ3 directions. It was found that this effect became more marked as σ1 (pre stress) was increased. The effect of the test load on the velocities became less anomalous under higher load. Preferred fracture orientations perpendicular σ2 and σ3 were found in specimens that underwent induced tensile fracture testing. The second project involved the testing of sandstone core obtained from the Carboniferous sediments of New Brunswick. Preferred fracture orientation occurred in the core that underwent induce tensile fracture testing and the overall fracture orientation trends had a spatial and possibly a chronological nature. Pulse velocity testing of three sandstone cubes showed anisotropy with the slow velocity corresponding to the vertical stress.