What do we mean by a ground model – the Fookes geomodel legacy

The first Glossop lecture by Professor Fookes in 1996 established the importance of the geological model in predicting ground conditions in engineering geology. The concept of the geological model was expanded in his 2000 paper on ‘total geology’, and this becomes the ‘geomodel’ in a 2015 book. Fookes was clear that the a priori geological model/geomodel developed from existing knowledge and site observations and was fundamental to planning and interpreting the ground conditions data that emerged from investigations. A geological model was referred to in the first iteration (2007) of Eurocode 7 and fed into a geotechnical design model. This usage was reaffirmed in 2022 within an overall Engineering Geological Model Framework by IAEG Commission 25. In Hong Kong the 2007 engineering geology manual identified a geological model as feeding into a ground model and then into a geotechnical model. The expression ‘ground model’ has subsequently emerged as providing a synopsis of the ground conditions that feeds into geotechnical design. This is recognized in the second iteration of Eurocode 7 and is in the 2023 CIRIA guidance on Geotechnical Baseline reports. The Society for Underwater Technology 2022 Report refers to the ground model and defines it as a database of available information that encompasses written reports, the database of collated information and the geotechnical risk register. Given these different views it is necessary to agree what constitutes a ground model, as this has important implications for contract documentation and establishing the legal responsibilities of all ground engineering professionals.