Going underground – modelling geology and geotechnical constructions for infrastructure projects

Synopsis:

Densification of the urban space drives more infrastructure projects below ground. By unleashing the power of parametric design in Grasshopper and dynamic 3D modelling for geology in Leapfrog Works, we have in recent years redefined how we plan, design and execute large-scale infrastructure projects.

Learning Objectives:

1. Learn why a 3D ground model can help make the right informed decision and communicate the uncertainty of a material you cannot really see from above ground 
2. How parametric design is used in infrastructure projects for the design, optimization, execution and documentation of geotechnical constructions, such as deep excavations and tunnels
3. Gain insight in how we transformed our engineering workflow by adopting new design tools and took a giant leap into the world of parametric design for infrastructure projects 

Body:

“Since the underground space is becoming more congested, especially in urban environments, new projects are increasingly more complex to plan, design and build. Building underground is expensive, time-consuming and often complex, with high risk of negatively impacting the surroundings due to vibrations, ground water lowering and so on. To design and build better, we must do it smarter. There is therefore an emerging need to improve the geotechnical toolbox so that projects may transform from a conventional, linear design and construction workflow, to a more agile workflow where model management and engineering analysis is part of an iterative process.
For some time now, engineers at the Norwegian Geotechnical Institute alongside (and inspired by) partner consultancy Geovita, have adopted new ways of creating and using parametric 3D models in their engineering design, from idea to construction. This new way of working has successfully been adopted on a few ongoing major infrastructure projects in Norway.
Whether for a new tunnel development, or an urban deep excavation project, the team begins by collecting all the available ground investigation data into a 3D ground model using Leapfrog Works. The ground model, which may be dynamically updated with new drilling results on-the-fly, is used as the common knowledge base for geotechnical design, and to communicate ground risks and uncertainties to project stakeholders. By ensuring that all available ground data is compiled in a single model and using this as input for further analysis and design, one can ensure the coherence between ground data, the individual engineering analysis and the designed geotechnical solution. In terms of quality assurance, cross-validation and model versioning are important factors. These actions are often lost when manually drawing stratigraphic cross-sections for use in the geotechnical analysis.
The 3D ground model is successfully applied for: (1) Visualization of geotechnical uncertainty, (2) communication of underground conditions and its associated risks to project stakeholders, and (3) efficiently applying the model as basis for efficient geotechnical design.
Secondly, all underground structural designs, such as retaining walls and rock support, are developed as parametric models in Grasshopper. Exports, such as bedrock and lithological surfaces from the Leapfrog ground model, is used as input to Grasshopper as boundary units for the geotechnical designs. When building parametric models, full control is ensured in complex designs, providing key features such as material quantities and georeferencing on each object, and facilitating frequent adjustments of geotechnical models to ground conditions.