Visualising the sub-surface

Geological engineering is fraught with complex challenges, namely the inability to see underground. Roads and Infrastructure explores how 3D modeling can offer a solution.

Melbourne’s West Gate Tunnel is one of the largest diameter bore excavation projects in the world and the second largest ever undertaken in the Southern Hemisphere.

When completed, the tunnel will run six kilometres, with its construction estimated to generate two million cubic metres of earth and rock spoil material. Project Manager, Transurban, faced a significant instability challenge.

Ground by its very nature is structurally complex and variable, with even the slightest disturbance altering its internal physics.

To address the unpredictable ground issue, Transurban engaged geotechnical services firm, Golder Associates, who undertook a geological assessment of the surrounding area.

Using Seequent’s 3D dynamic modelling software for ground engineering, Leapfrog Works, Golder Associates assessed geological risks before communicating these to relevant design and build stakeholders.

Seequent, a global company with headquarters in New Zealand, designs software solutions for civil engineering and construction companies working in the sub-surface area.

Without an understanding of terrain, time- and money-wasting problems are likely to arise in geologically complex areas.

According to Seequent Civil and Environmental Industries General Manager, Daniel Wallace, the West Gate Tunnel passes through variable sedimentary and igneous deposits, which reflects the complex geological and geomorphological processes of the region.

“We create software that allows people to visualise what they can’t see above the ground by generating a 3D visualisation of what the sub-surface looks like,” Mr. Wallace says. “It’s a bit like Google Earth but underground.”

Mr. Wallace says while taking samples and analysing them isn’t new, outputs were previously designed in CAD or 2D cross-sections on paper.

“Cross sections are difficult to communicate with as they only show what has been found in relation to a particular sample.”

Mr. Wallace says Seequent’s 3D visualised approach enables users to construct a holistic site image and narrative.

“If all you have is a 2D drawing, it’s actually quite difficult to effectively communicate,” Mr. Wallace says.

“What we’re hearing from users is that Leapfrog provides a deliverable, which matches the way humans think. We don’t think in 2D cross sections, we think in 3D.”

According to Mr. Wallace, Seequent hopes to give geological engineers a larger voice in the design process.

“We hear all the time about infrastructure deteriorating – a better understanding of the ground and how it works will eliminate that,” Mr. Wallace says.

“We view it as being responsible custodians of the land – facilitating the construction of sustainable infrastructure with a focus on safety and longevity.”

According to Mr. Wallace, Leapfrog generates an insight into what users can expect to find underground through site investigation data inputs.

“A core data point is bore hole samples, and we have access to all the major bore hole databases,” Mr. Wallace says.

“Users can input any number of data formats such as cone penetration test data, topographic information, geological information systems data or anything that holds sub-surface information – they can even digitise old geological maps.”

Mr. Wallace says once all relevant data is loaded onto the system, Leapfrog generates a 3D model that users can drape topography over – producing a photo realistic representation of their site.

“Users can then insert building information modeling and design data to observe how planned works will interact with the geological nature of the site,” Mr. Wallace says.

He also says that transforming site investigation data into a photo realistic image allows people not familiar with geological information to better understand potential problems.

“Combining disparate data types to create a 3D model of the sub-surface, which can be combined with digital design, gives users a complete picture of what the project will look like – in addition to problems they might face,” Mr. Wallace says.

“As you edit the model over time, and new data becomes available, or the project shifts, Leapfrog’s cloud-based memory tool can create a trail that lets users go back in time for comparative purposes,” Mr. Wallace says.

According to Mr. Wallace, this assists Seequent clients, who typically work in mining and civil construction, make better decisions throughout the course of their project.

“In the civil space, it’s all about how new infrastructure will interact with existing ground conditions,” Mr. Wallace says. “If contractors want to build a tunnel though a hill for example, they need to think, will we find rock? What kind of rock? Will we find fractures? Will water leak through when it rains?”

Mr. Wallace says these questions can be answered by Leapfrog, allowing engineers to better design fit for purpose infrastructure.

“Engineers can take the information provided by Leapfrog and analyse what elements of the design needs particular attention,” he says. “This saves time and money, as users can trust they have a robust design prior to excavation.”

Mr. Wallace says that within a civil construction context, Leapfrog users are typically geological engineers.

“Leapfrog enables geological engineers to work closely with civil engineers when designing infrastructure, converting what has traditionally been a serial workflow into a parallel one,” he says.

While a serial workflow is chronological, one step after the other, a parallel workflow involves simultaneous processing and interdisciplinary collaboration.

“A civil engineer designing a tunnel can’t function in a vacuum. They need to work in an integrated way,” says Mr. Wallace.

Another point of difference for Leapfrog is its licensing model, which effectively lets users “rent” the system when required.

This business model, according to Mr. Wallace, aligns with the wider trend of digital transformation and joint tenders.

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