What is 3D geology modelling?
Aurecon regularly put on ‘Lunch & Learn’ sessions for their engineers. This is a great opportunity to here from other areas of engineering and hear about some cool engineering technologies being used across the company – yes, I used the words ‘cool’ and ‘engineering’.
Recently, an engineer from the geotechnical team delivered an interesting presentation on 3D geology modelling and it’s use on large infrastructure projects. As I am working in the bridge design team, I decided to go along and get some time away from superstructure ‘stuff’.
3D geological modelling is a key ground engineering technique, which is increasingly being utilized on large and medium sized projects, particularly for large linear infrastructure projects (think tunnelling and mining). Over the past two years, Aurecon has aligned to the use of the software ‘Leapfrog Works’, although a range of software applications exist. This was of interest to me, as I know it was used for the West Gate Tunnel Project (WGTP).
3D geology modelling is transforming the way ground engineering data is acquired, analysed, and communicated. Some of the key advantages are:
- Improved ability to compile large ground information datasets, which in turn improves the way you can capture and communicate geological complexity;
- Enhanced data visualisation, which aids with interpretation of ground risks and improves our ability to detect problems with input data or with the ground model;
- 3D geology modelling is visually engaging, which can enhance client or stakeholder presentations;
- Improved process efficiency and semi-automated section production;
- Dynamic integration with centralised ground investigation databases, allowing for rapid propagation of changes and revisions
- A centralised, online environment, that enables improved collaboration on modelling projects and allows for tracking of changes and improved model QA.
On the WGTP, 3D geology modelling (using Leapfrog) was used for the 6km of tunnels and supporting road upgrades to determine spoil volume, of which the Leapfrog model anticipated to be over 2 million cubic metres; this included earth and rock spoil material. This ability offers clear advantage for tendering purposes; how many spoil trucks will I need, etc.
In addition to this, it was also used to: highlight risks at the portals, model aquifer units used in hydrogeological impact studies, generate 2D sections for geotechnical ground movement modelling and was key for communicating risks/design to the client.
However, GROUND IS RISK!!!!!! (as a pen flies across the room towards Mr. Dale)
Like anything within the dark art of ground engineering, there is some considerable risk involved. 3D geology models do not just ‘magically’ understand everything about the ground and, like any software, require information input. Models are generally built from borehole data, ground investigations, etc. Therefore, most of the model will be based on interpolation and assumptions of ground conditions based off the data available.
Ultimately, clear communication of uncertainty remains a major risk, and the importance of good geological expertise is paramount when using 3D geological modelling. But the process and softwares available clearly offer a powerful tool for modelling and understanding the potential risks.
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Dan, where does the data come from that feeds the model please?
Scratch that Dan, I see you have answered it at the bottom. Does the amount of data required to drive the model exceed that we would normally seek though?
About a thousand years ago my MSc thesis was on this subject and I wrote a progamme (or a series of programmes) in AutoLISP to use AutoCAD as a 3D viewer for borehole data
Over time BGS has connected the borehole data submitted to them ( we used to do this on every project until they became commercial) There is a crude 3 D geological model of the UK on the BGS site that is improving with time
At a local level there are a number of programmes that database borehole information and generate 3D model . The most widely used is GiNT…I’ve used this for years but it has always been truly awful. The current release of GEO 5 allows the generation of 3 D GEO models. There are neutral interchange formats…the one that’s most neutral is the AGS format. This permits spatial data and geotechnical data associated with spatial points all the way to any in situ and laboratory data associated with the investigation point.
The problem is that there is no longer common ownership so there are partial data sets all over the place.