When do you need geotechnical design, and why should the geotechnical engineer be involved early?

The ground conditions can have a major impact on the solutions, costs and progress of a construction or civil engineering project. If challenges are only discovered once the project is well advanced, it may be necessary to change the foundations, excavation pit or other solutions at a point where there are fewer options and changes are more costly.

Geotechnical design is therefore about more than documenting that a project meets the requirements. By involving a geotechnical engineer early, the ground conditions can be assessed and technical solutions adapted before important choices are locked in.

But when is geotechnical design necessary, what is the difference between a geotechnical assessment and design, and what does the geotechnical engineer actually do throughout the project?

What is geotechnical design?

Geotechnical design covers analyses and calculations that form the basis for how a construction or civil engineering project is to be adapted to the ground conditions.

The design is based on available data, ground investigations and applicable regulations. The result is technical solutions describing how the project can be carried out safely.

Depending on the project, geotechnical design can include, among other things:

• foundations
• excavation pits and sheet piling
• slope and area stability
• settlement assessments
• ground improvement

The aim is to develop solutions that ensure safety, while being adapted to the project and the actual ground conditions on site.

What is the difference between a geotechnical assessment and geotechnical design?

The terms are often used interchangeably, but have different purposes.

A geotechnical assessment is often carried out early in a project or as part of the building application. The purpose is to document whether the ground conditions have been sufficiently assessed, and whether the project meets the applicable safety requirements.

Geotechnical design goes a step further. Here, the technical solutions to be used during construction are developed and calculated.

A geotechnical assessment can therefore conclude that the project also requires geotechnical design.

Has the municipality asked for geotechnical documentation in connection with your building application? Read more in our article «The municipality requires a geotechnical assessment – what you need to know before your building application can proceed».

When is geotechnical design necessary?

The need depends on the size and complexity of the project and the ground conditions on site.

Geotechnical design is often relevant for:

• residential and commercial buildings
• roads and transport infrastructure
• quays and port facilities
• larger groundworks
• excavation pits in built-up areas
• areas with challenging ground conditions or quick clay

The scope can vary considerably, from simple foundation assessments to extensive stability analyses and design of geotechnical structures.

It is therefore not only the size of the project that determines the need. The ground conditions and the solutions to be built also have a major impact on what geotechnical advice and design is needed.

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What does the geotechnical engineer do throughout the project?

The geotechnical engineer can contribute throughout the project's lifetime, from the first assessments until the construction work is completed.

Early phase: Clarify the ground conditions before solutions are locked in

At the start of the project, the available information about the ground conditions is assessed. If existing data is not sufficient, ground investigations are planned and interpreted to provide the necessary basis for design.

Getting an overview of the ground conditions early gives the project a better basis for further choices and design.

Design: From ground conditions to buildable solutions

Based on the ground conditions, geotechnical calculations and analyses are carried out. Solutions are then designed, which may include foundations, excavation pits, stability measures, retaining structures or ground improvement.

The design is carried out in close collaboration with the other consultants, so that the geotechnical solutions are adapted to the rest of the project.

Construction phase: When reality does not quite match the basis

Even with a good design basis, the conditions uncovered during construction may differ from what was expected. The project may also change along the way.

In such cases, the geotechnical engineer can provide advice and assess necessary adjustments, so that the solutions can be adjusted without compromising safety.

Why does it pay to involve the geotechnical engineer early?

Good geotechnical solutions are not just about meeting official requirements. They can also reduce risk and contribute to a more efficient and predictable construction project.

The right geotechnical design can, among other things:

• reduce the risk of settlement damage and stability problems
• provide a better basis for choosing a foundation solution
• reduce the need for changes in the construction phase
• protect surrounding buildings and infrastructure
• contribute to safe and cost-effective execution

Early geotechnical assessments can identify challenges before they affect progress and costs. When the ground conditions are taken into account while the project still has room to manoeuvre, it is also easier to adapt the solutions to the rest of the project.

Geotechnical advice from the early phase to complete design

In practice, geotechnical design is about understanding the interaction between the ground conditions and what is to be built. The earlier this knowledge comes into the project, the better the basis for choosing solutions adapted to both the ground and the project's other conditions.

Head Energy Geo provides geotechnical advice from the zoning phase and pre-project and concept phase to detailed design. Our geotechnical engineers have experience with various foundation solutions and projects with challenging ground conditions, including the construction of structures and infrastructure on bogland.

We can also assist with assessments of local and area stability in accordance with NVE's quick clay guidelines, and carry out geotechnical ground investigations when the project requires more knowledge of the ground conditions.

How can Head Energy Geo help?

Within geotechnics and ground investigations, Head Energy Geo offers, among other things:

• assistance in the zoning phase
• RIG/RIGeo (geotechnical and engineering geology consulting) in projects
• assessment of local and area stability
• foundation solutions, including shallow foundations and pile foundations
• sustainable solutions, including building on bogland and preserving bogs
• geotechnical assistance in due diligence processes
• ground investigations and geotechnical design from A to Z
• independent control (UAK) RIG TK2

Head Energy Geo assists both public and private clients throughout Norway with geotechnics, ground investigations, engineering geology, environmental engineering and geology.

Are you starting a construction or civil engineering project and unsure which geotechnical assessments or investigations the project requires? Contact Head Energy Geo for a professional discussion about the ground conditions and how we can support your project.