VGS Short Course on Critical State Soil Mechanics for Practical Engineers

Taught by Mike Jefferies, Dr. Dawn Shuttle, and Dr. Marcos Arroyo

Sunday, 26 October 2025 – Tuesday, 28 October 2025

Executive Hotel & Conference Centre, 4201 Lougheed Highway, Burnaby, BC V5C 3Y6

Purpose and Background:

This course on the application of critical state soil mechanics (CSSM) in practical engineering has been given for VGS twice before (in 2015 and 2020) and a further twelve times worldwide including in Brazil, Chile, South Africa, Sweden, and the US. Some 400 engineers have now participated in this ‘continuing education’ training.

Motivation for another CSSM course came from EGBC. With various recent initiatives, including the Global Tailings Standard and associated guidance, EGBC wanted a course on the relevant soil mechanics (ie CSSM) as part of their continuing education offering for 2025. After brief discussion, it seemed more appropriate to continue with VGS and over the usual three days rather than the one-day envisaged by EGBC. However, there has been some developments within the subject that require more than ‘2020 repeated’.

There are two steps in applying CSSM: i) determination of soil properties; and, ii) measuring soil state. The overall behaviour (strength, liquefaction potential etc) is the product of both properties and state. The CPT has always been the basis of step (ii), but there are uncertainties in how CPT data is processed to give soil state because the processing is affected by soil properties. To date, the effect of properties on the CPT has based on cavity expansion theory, but that is only an analogue and requires calibration. Uncertainties arise with that calibration.

Recent developments within the finite element method now allow direct and realistic simulation of the CPT. These developments supersede cavity-expansion as the basis for understanding the CPT. One group contributing to these new finite element approaches is the Technical University of Catalonia (UPC, Barcelona) and Marcos Arroyo, who leads their work has agreed to contribute that aspect to the 2025 CSSM course. As Marcos uses the CASM soil model, this will be introduced alongside NorSand.

Course Overview:

The origin of the critical state approach to soil behaviour, in 1935, was avoiding liquefaction failures of earth dams. Recent liquefaction failures of Fundao, Cadia and Brumadinho dams have produced renewed interest in the approach, as these three dam failures were all investigated using a critical state perspective. Arguably, a critical state approach is now expected for the engineering of tailings dams worldwide.

Any soil can exist over a range of void ratios. The particular void ratio and confining stress, of any element of soil, controls its mechanical behaviour. Understanding how this control arises has been a thread within theoretical soil mechanics over many years, leading to what we know today as critical state soil mechanics (CSSM). Only a few soil properties are needed yet the wide range of soil behaviour is captured, and with considerable detail: CSSM is the only framework that provides both simplicity and accuracy. CSSM also applies to all soil types, from clays to at least coarse-sand.

CSSM exists within the framework of theoretical plasticity, but that framework is something rarely taught in civil engineering programs even though the ideas are simple. The effect is that nearly all geotechnical engineers suffer culture shock when reading about CSSM – it is a different language, and that difference is an enormous block to understanding. Reading and/or attending lectures is not enough. Understanding CSSM requires computing a stressstrain curve using CSSM yourself, in Excel, so you can see how the equations play off each other. The understanding from developing a simple model in Excel then allows confident use of ‘industrial quality’ software – CSSM is no longer a mysterious ‘black box’.

This course covers soil properties and their measurement, critical state theory, and processing of CPT to determine soil state. Both lectures and tutorials are used, with the particular aim for the tutorials being that all attendees will realize the simplicity – and power – of CSSM for themselves. This particular course will extend the content to include a wider perspective of critical state theory (using both NorSand and CASM) and the most recent developments in evaluating CPT data to determine soil state.

The course is taught over three days, each nominally 8 hrs. The schedule for the three days is shown below. The number of attendees is limited to 40, based on experience, to ensure adequate attendee-tutor time for all.

Instructor Bios:

Mike Jefferies, PEng. Mike was educated at King’s and Imperial (London), being tutored by Bob Gibson, Alan Bishop and Peter Wroth (all Rankine Lecturers). Despite working in industry throughout a 50-year career, Mike maintained an interest in advancing engineering science and contributed some 100 papers to the literature; of these papers, the 1985 ‘state parameter’ has become one of the most influential papers ever published by Geotechnique. A particular interest has been critical state theory, which resulted in the ‘Soil Liquefaction’ text book by which he is most commonly associated. The NorSand model, now embedded within standard geotechnical software, and used for analysis of many recent dam failures, was derived by Mike. He was a member of the Board retained to assess the 2018 Cadia dam failure.

Dr Dawn Shuttle, CEng. Dawn was educated at Manchester University, being tutored by Ian Smith who led the development of modular and open-source finite element programming with the associated textbook now in its 5th Edition. In the thirty-five years since her PhD in the finite element method, Dawn has worked primarily as a consulting engineer and focused on application of numerical methods across a wide spectrum of civil engineering work. Publishing some fifty papers, with a further three invited chapters in engineering books, Dawn was the editor for the ASCE’s Compaction Grouting Guide. Dawn was the principal developer for implementation of CSSM within numerical codes, with her software being used for the analysis of the Fundao, Cadia, and Brumadinho dam failures. In situ testing has been a particular interest, with her work on the CPT attracting a Telford Premium in 2016; that software is fondly known as the CPTwidget and forms part of the course.

Dr Marcos Arroyo. Marcos is Professor of Geotechnical Engineering at Polytechnic University of Catalonia (UPC) in Barcelona. Graduating in civil engineering in Madrid, he obtained a PhD from Bristol University. He worked as researcher at Politecnico di Milano and University College London before joining UPC. His research relies on different numerical techniques (DEM, FEM, PFEM) to address questions of engineering interest, with a particular emphasis on geotechnical site characterization; Marcos has published more than 200 contributions to the literature and is active in several international committees, notably ISO TC182 Geotechnics and CEN TC250/SC7/, where he contributed to drafts of second generation Eurocodes EC7.1 and EC7.2 He is the current Secretary of the ISSMGE Technical Committee on In situ testing. Marcos led the CIMNE team carrying out a forensic numerical analyses of Brumadinho Dam failure for the Brazilian public prosecutor office.

Andrea Lougheed PEng. Andrea is a senior geotechnical engineer and Soil Mechanics Lead for BGC Engineering Inc. Based in Vancouver, she has nearly 20 years of experience specializing in soil mechanics over a wide range of geotechnical projects from large transportation design-build to tailings facilities. In particular, this experience includes static and seismic liquefaction assessments using soil-specific NorSand parameters and coefficients with the CPTwidget. She has served as the Chair and Section Director for the Vancouver Geotechnical Society (VGS), Co-Chair for the 69th Canadian Geotechnical Conference, and Section Representative and Vice-President Finance for the Canadian Geotechnical Society (CGS). She is the recipient of CGS’s A.G. Stermac Service Award, International Young Geotechnical Engineers Conference Travel Award and Early Achievement Award. She tutored the VGS’s 2020 critical state soil course and taught the University of Alberta’s 2025 critical state soil mechanics course.

Dallas McGowan, PEng. Dallas is Vice President at ConeTec, where he leads Oil Sands, Quality, Research, Geophysics, and Data Reporting initiatives. A UBC graduate with some fifteen years of experience in geotechnical site investigations and tailings management, he has authored numerous publications about in situ testing across a wide-variety of conditions. Dallas is passionate about advancing innovative solutions in site characterization. Dallas taught the module on CPT procedures for the University of Alberta’s 2025 critical state soil mechanics course.

Course Schedule

Date: Sunday, 26 October 2025 – Tuesday, 28 October 2025

Time: 7:30 am to 5:00 pm

Location: Executive Hotel & Conference Centre, 4201 Lougheed Highway, Burnaby, BC V5C 3Y6

Breakfast and lunch will be provided, as will snacks and beverages during the morning and afternoon breaks.

Space is limited to 40 participants. To allow for attendance from multiple consultants and agencies we will be capping registration at 5 people per organization for the early bird period. If spaces remain following the early bird period they will be opened at that time.

Online registration will be available the week of September 8, 2025.

For additional information or questions, please contact:

Tyler Southam (Tyler.Southam@tetratech.com)