New Developments in Geotechnical Investigation Modelling for Tunneling Projects

Author(s) F. Noori, W. Hoyle, A. Plazek
Presented at the Tunnelling Association of Canada TAC 2023 – in Toronto from September 24-26. The theme of this year’s event, “Smart Solutions, Future Growth”, will be highlighted throughout the conference through keynote speakers, plenary presentations, technical sessions, networking, and a trade exhibition to showcase tunnelling and trenchless technology throughout Canada and around the world


Many tunneling projects require information such as shallow foundation characteristics, depth to competent bedrock and the hydrogeology of the bedrock units. More often than not, the underground complexes include portals, shafts, caverns, permanent and temporary access tunnels.

The required information for the underground design includes rock mass quality, jointing, RQD, hydraulic conductivity and other information relating to tunnelling. This is a wide variety of different data types that are collected and calculated using different methods, and it can be difficult to manage and visualize this information effectively. A digital workflow for the field collection of data can be highly beneficial to most effectively collect and store these large sets of data. A 3D geological model could be produced utilizing the digital database collected in the field and 3D modelling software (such as Leapfrog Works by Seequent) for the storage and display of geotechnical data collected from the geotechnical investigation program. This approach allows for storage of all geotechnical data in a single model space with true 3D viewing of collected data by geotechnical investigations including drilling boreholes, insitu testing and sampling and laboratory testing. The project model then can be broken down into refined models for each distinct portion of the project, which allows for customized usage of the data without affecting the overall project model or the underlying data. One of many challenges related to the geotechnical investigation of large infrastructure projects is that there are very distinct geotechnical elements in different areas of the project site and the need to integrate these elements into one cohesive investigation program, and the method to organize and display the results in a way that meets the needs of each distinct design team. Often, parts of the underground complex has unique challenges, for example due to being situated at the bottom of a lake.