Classification of sandstones and shales in the Sydney region: A forty year review

P. J. N. Pells, G. Mostyn, R. Bertuzzi and P. K. Wong

The classification system developed in 1978 by a sub-committee of the Australian Geomechnics Society in association with guideline allowable bearing pressures on the Triassic sandstones and shales of the Sydney Basin has proven to be useful as a communication tool on many and varied projects in Sydney and its surrounds. However, the classification system has also been misused.

In this 2nd update of the original paper, the authors:

  • indicate uses of the associated classification system, or components thereof, for design of prestressed ground anchors, and for preliminary groundwater analyses,
  • show that a modified system is appropriate for linkage to tunnel support design,
  • document why the system should not be used in assessments of slope stability, excavatability and rock cutting, and
  • expand the guidelines for foundation bearing pressures and socket side shear values based on extensive research testing, and field experience, gained in the 40 years since the original publication.