ABSTRACT
The Wianamatta group is a major geological sequence in the Sydney Basin. Shale is the most abundant rock type in this group and is the upper material over a large region of suburban Sydney. Bringelly shale, which is the top layer in the Wianamatta group, is highly compacted, weakly cemented, and contains significant amounts of swelling clay minerals. With conventional drilling techniques core recovery of this shale is low and it is difficult to obtain samples for mechanical testing. To obtain some base data on the strength and stiffness of the shale the intact material has been crushed and reconstituted. Isotropically consolidated undrained triaxial tests have been performed on specimens for a range of stress levels, over-consolidation ratios and initial porosities. The method of sample preparation, which was varied to produce low porosities similar to the natural shale, has been found to significantly affect the mechanical response.
