Applying 3D Geological Modelling Techniques to Geotechnical Engineering Problems – Advantages, Pitfalls, and “Getting the Geology Right”

The geotechnical ground model is the fundamental basis of geotechnical engineering. 3D geological modelling software is now routinely utilised to assist with solving geotechnical engineering problems – this allows rigour to be applied to ground model development, and facilitates early identification and assessment of geotechnical site issues. A good 3D conceptualisation improves connectivity between different engineering disciplines and can improve project efficiency. However, for a model to be useful, it must be founded on robust geological principles, and the value of high-quality input data and expert user guidance cannot be understated. This paper presents several project case studies from Victoria, Australia, demonstrating how the utilisation of 3D geological modelling techniques 1) expanded our understanding of the sites’ geotechnical and hydrogeological ground model, 2) aided identification of the geotechnical failure model, and 3) assisted site investigations. We highlight the ways in which modelling played an essential role in clarifying the site geology, geotechnical parameters, and hydrogeology, and where it helped to refine the proposed geotechnical design. When used effectively, 3D modelling can synthesise large datasets to help identify and interpret crucial features and sources of geotechnical risk. We note that while 3D geological modelling tools are now routinely utilised on large infrastructure projects, they remain relatively under-utilised on small- and medium-sized projects, even where the geology is complex and/or the geotechnical risk is high. We demonstrate the value of 3D geological modelling combined with geological/geotechnical knowledge, and how it assists in developing ground understanding for geotechnical engineering projects of all sizes.