Unsaturated soil mechanics and the effective stress in design practice: with application to retaining wall design and CPT interpretation

A/Professor Adrian Russell


Unsaturated soils are widely encountered and need to be dealt with in many engineering problems, for example foundations, fills, embankments and slopes. In many cases true predictions of performance and assessments of safety cannot be made without use of unsaturated soil mechanics.

In this presentation it will be demonstrated how practitioners can apply unsaturated soil mechanics and the effective stress concept to a retaining wall design problem. The important role of suction and its contribution to the effective stress, stiffness and strength will be highlighted. The presentation will also demonstrate how the effects of suction can be quantified, for example using cone penetration testing and laboratory testing. The pitfalls of ignoring the effects of suction will be highlighted.

About Adrian RussellAdrian Russel

Adrian is an Associate Professor at UNSW and leads a number of research projects and themes focussed on fundamental mechanics, analytical modelling, and novel experimentation related to structures interacting with unsaturated soils. He has written more than 75 research papers, and has been awarded many times for his research. He is Secretary of TC106, the Technical Committee on Unsaturated Soils within the International Society for Soil Mechanics and Geotechnical Engineering. In 2014 he received the International Innovation Award from TC106 for his research on the CPT and retaining walls in unsaturated soils. He has worked in academic environment for 16 years, and as a consulting geotechnical engineer for three years.

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