Some physical properties of sandstones lithified under the influence of differential stresses

Abstract

The result of two experiments are discussed in this thesis. The first experimental project involved the testing of concrete cubes solidified under the stress conditions of δ1 >δ2=δ3 where δ1 was the experimental variable. Pulse velocity anisotropy occurred with the slower velocity in the δ1 direction and the two faster (and equal) velocities corresponding to the δ2 and δ3 directions. It was found that this effect became more marked as δ1 (pre stress) was increased. The effect of the test load on the velocities became less anomalous under higher load. Preferred fracture orientations perpendicular to δ1, δ2 and δ3 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 induced 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.