Sydney Chapter

Problematic Soils

Prof David Airey

The presentation will provide a brief summary of the activities of AGS over the last 2 years and then present a technical presentation on the topic “What is the Problem with Problematic Soils?”

A large number of soils are considered to be problematic (eg. Collapsible soils, Expansive soils, Peat, Silty soils, Liquefiable soils). The talk will briefly cover the factors that lead to soils being considered to be problematic (soil type, site investigation, testing, modelling, experience).

A case study of an unusual problematic residual soil, limonite from New Caledonia will be presented to illustrate some of the challenges. Limonite is a residual soil produced by the decomposition of magnesium silicate (olivine) rocks in tropical environments. During weathering most of the original rock is leached away leaving only its iron content, which is precipitated out in the form of iron sesqui-oxides to create a soft and highly porous soil up to 70 m deep. This material presents challenges in classification, compactability and in- situ has a high variability in strength and stiffness.

The talk will conclude with some thoughts on the need to recognise the challenges presented by the ground, and how we can remove the problem from problematic soils.

Speaker biography

David Airey graduated from Cambridge University with BA and PhD degrees before moving to UWA for 2 years and then to the University of Sydney where he now holds the position of Professor. His interests are in experimental Geotechnics, instrumentation and soil behaviour.

His current research interests include dynamic compaction, bio-cementation, rock bolt corrosion and effects of CO2 sequestration on coal and other rocks, and he has many years experience in laboratory testing of problem soils.

Engineers Australia members participating in AGS technical sessions can record attendance on their personal CPD logs. Members should refer to Engineers Australia CPD policy for details on CPD types, requirements and auditing guidelines.