A public talk by Professor D. Vaughan Griffiths, Head, Department of Civil and Environmental Engineering, Colorado School of Mines

Soil and rock are among the most variable of engineering materials, but geotechnical engineers rarely take account of this variability directly. They are more likely to assign a single conservative property to the entire site and ignore the variability. This usually leads to an assessment of safety using a “Factor of Safety (FS)” where FS>1 implies safety and FS<1 implies failure. A more scientific approach tackles the soil variability directly leading to a “Probability of Failure”. The tricky part is then to decide what is an acceptable probability of failure given the consequences of failure and the available resources. This lecture will describe some methods for assessing the probability of failure of geotechnical systems ranging from quick “back of the envelope” calculations to computational intense methods requiring supercomputers. Some of the benefits and shortcomings of these methods will be discussed with practical examples.

D. Vaughan Griffiths PhD, DSc, PE, D.GE, C.Eng, FICE, Dist.M.ASCE is a Professor and Head of the Department of Civil and Environmental Engineering at the Colorado School of Mines, USA. His research interests lie in application of finite element and risk assessment methodologies in geotechnical engineering, and his papers on slope stability analysis are among the most highly cited in the geotechnical engineering literature. He is the co-author of three textbooks that have gone into multiple and foreign language editions on Programming the Finite Element Method, Risk Assessment in Geotechnical Engineering and Numerical Methods for Engineers. He gives regular short courses worldwide on risk assessment in geotechnical engineering and slope stability analysis. He has acted as a consultant to industry on projects ranging from landslide analysis to petroleum geomechanics. He was the inaugural Suzanne Lacasse Lecturer in 2016 and in 2017, was named the Cross-Canada Lecturer by the Canadian Geotechnical Society and received the H. Bolton Seed Medal from the ASCE/Geo-Institute. He gave the TH Wu Distinguished lecture in 2021, the Wilson Tang lecture in 2022 and has been named the Terzaghi Lecturer for 2026. He was awarded a Fulbright Distinguished Chair for 2023 to work at the University of Newcastle, NSW. He served on the Board of Direction of ASCE from 2010-2013 and was inducted as a Distinguished Member of the ASCE in 2020.

Professor Griffiths is a UWA Gledden Visiting Fellow, working with Professor Yuxia Hu in the UWA School of Civil, Environmental & Mining Engineering.