Understanding the Effects of
Structure and Bonding in the Bringelly Shale


Ezzat William

Centre for Geotechnical Research
University of Sydney, Australia


Shale is the most abundant rock type in a group called Wianamatta. The group is the major geological sequence in the Sydney Basin. Bringelly shale, the major formation of the group is comprised of claystones and siltstones with occasional sandstone layers. Weak cementation and presence of swelling clay minerals have caused a number of problems with structures founded on Bringelly shale. The results of triaxial tests on reconstituted specimens are compared with the behaviour of a natural rock specimen. In order to study the de-structural behaviour of the shale, the material was subjected to high stress so that low porosity structure can be produced. Same materials that have experienced higher stress show significantly reduced frictional strength and pattern of behaviour inconsistent with critical state concepts.

Keywords: Sydney Basin, Bringelly shale, Structure and Bonding, rocks


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