Grant: Discovery Grants Program - Individual

In Canada, geotechnical design is now almost entirely reliability-based, at least approximately. Our major geotechnical design codes, the Canadian Highway Bridge Design Code (CHBDC) and the National Building Code of Canada (through the Canadian Foundation Engineering Manual, CFEM) provide load and resistance factor design solutions, intended to achieve target reliability levels, for almost all geotechnical designs. Much work is still required, however, to improve code calibrations and hence both improve safety and decrease cost. Some of the standard geotechnical systems (e.g., shallow and deep foundations) have been examined carefully in the last few decades, and their total resistance factors established with reasonable accuracy for various degrees of site and model understanding and for various consequence levels. However, the following are some of the most important areas still in need of the research proposed herein: 1) Seismic geotechnical design: There is a disconnect between what current theory suggests regarding the reliability of geotechnical systems designed against seismic loading and what is observed in practice in Canada. Our most sophisticated models suggest that our designs are unsafe against earthquakes and yet we have not seen many failures. What is the source of this discrepancy? Is it just that we have been "lucky" and not had any earthquakes big enough to test the reliability of our designs? Or are our theoretical models missing critical elements that contribute to overall system reliability? This research aims to address these questions and calibrate the required geotechnical seismic design provisions. 2) Ground anchors: Despite their importance in stabilizing structures and geotechnical systems, it is only in the last couple of years that investigations into the reliability of ground anchors have appeared. These investigations tend to be quite thorough, based on the random finite element method (which I pioneered years ago), but limited in scope. There is still much to be done before reliability-base design codes for a variety of ground anchors can be properly calibrated. 3) Retaining systems: There is still much to be learned about the reliability-based geotechnical design of traditional retaining walls, taking into account the spatial variability of the retained ground. 4) Embankments: One of the concerns that my CHBDC subcommittee has is how to properly design against so-called surficial failures? Surficial failures are not well defined, nor have they been studied probabilistically, yet their occurrence is an important ultimate or serviceability limit state. 5) Scour: In 2021 climate change impacts led to the failure of several important bridges in British Columbia due to stream-bed scour. There is much need to understand the probabilistic nature of scour and develop reliability-based designs to avoid this type of failure in the future.