Critical State Soil Mechanics: 125 years of history to current use
Mike Jefferies
About the presentation
This presentation was presented for the 16th Jennings Memorial Lecture 2018 recently hosted by the Geotechnical Division of the South African Institution of Civil Engineering.
Abstract
Any particular soil can exist over a range of void ratio (or its alternate identity, density). Critical state soil mechanics (CSSM) is a theory linking a soil’s void ratio to all aspects of its mechanical behaviour, and is presently the only theory to do this. However, there is a widely held perception that CSSM relates to an ‘over idealized’ model put forward by Cambridge University which has no relevance to real engineering (see Wikipedia…). This perception is wrong on many counts. This presentation considers the development of CSSM from a historical perspective, illustrating the simplicity of the underlying ideas, and the wide range of contributors, and which leads to a proper representation of soil behaviour in a formally generalized framework using the state parameter. This generalization works, with considerable detail, for real soils ranging from clays to sands. But this then raises the need to determine the state parameter in situ, presented in detail based on the Cone Penetration Test (CPT). There is particular application to liquefaction, the cause of many tailings dam failures.
About Mike Jefferies
Mike Jefferies is a registered civil engineer (Canada), and Senior Consultant (‘emeritus’) of Golder Associates, with some 40 years of experience, mostly consulting, but ten years of that with resource companies. It was the time with Gulf Canada Resources that had a great need to “push the envelope” and which led to the most significant of his contributions to engineering. A keynote speaker at international conferences, the Canadian Geotechnical Society’s Fall/2012 Cross-Canada Lecturer, the Slovenian Geotechnical Society’s Šuklje Lecturer in 2014 (on liquefaction), and awarded a Telford Premium in 2016 (for contributions to the CPT), Mike has published some eighty papers ranging across ice loading of offshore platforms through to rock fracture grouting. But, he is generally most known for the state parameter approach to soil characterization – an approach that has become one of the most cited innovations of the past twenty-five years of geotechnical engineering. The state parameter work led to an invitation to write a book on soil liquefaction, first published in 2006 and with a second edition in 2016. As will be evident from a quick glance at the book, Mike is an exponent of the heresy that geotechnical engineering must be based on applied mechanics, not geology, and that the critical state soil mechanics is fundamental, readily measurable, and something every geotechnical engineer should appreciate.
Venue location
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.