Geotest Sites
Norwegian Geotechnical Institute, Oslo / Norway
Scope
The Geotest sites research infrastructure managed by the NGI is a national research facility for geotechnical research. The six benchmark test sites are located in Norway and on Svalbard and have been developed as field laboratories for the testing and verification of innovative soil investigation and testing methods, and prototypes of geotechnical structures. The sites cover the soil conditions of soft clay, quick clay, silt and sand. As interest for the Arctic areas grows, one of the sites is in permafrost on Svalbard where detection, sampling, in situ testing and laboratory testing of frozen ground present significant challenges. NGI offers in addition a unique full-scale snow avalanche test site (Fonnbu/Ryggfonn) for studying triggering factors, avalanche dynamics and its impact on the design of mitigation measures.
The test sites serve as reference sites for the industry, public authorities, research organizations and academia. The benchmarked data can be used to develop soil material models, new investigation methods, new foundation solutions and advance the state-of-the-art.
Other Relevant Information
There is already a wide cooperation within the geotechnical community in Norway and abroad for the use of the sites. It is hoped that research at the test facility will provide more cost-effective and sustainable solutions within the building and construction, transportation and energy sectors and to mitigate the effects of climate change.
Various problems can be explored at these sites include (but are not limited to):
- Testing and benchmarking of in situ investigation/testing methods and instrumentations (CPTU, sampling methods, nonintrusive tomographical methods…etc)
- Field testing of foundation prototypes (monopiles, suction bucket, energy piles…etc). See, for example, a full-scale test of pile capacity
- Field testing of soil-structure interaction (piles, retaining wall, fill, cut…etc). See, for example, a full-scale test of a fill for road construction in Norway.
- Experiments for collecting geotechnical parameters to validate constitutive/numerical models (soil-structure interactions…etc).
- Full-scale testing of snow avalanches and safety measures (dams, screens).
| Facility Details | |
|---|---|
| Name | Geotest Sites |
| Short Name | NGTS |
| Owner | Norwegian Geotechnical Institute (NGI) |
| Location | Oslo / Norway |
| Website | Click Here to Visit Site |
| Contact | Thi Minh Hue Le |
| Head of facility | Jean-Sebastien L'Heureux |
| Construction year | 2016 - 2019 |
Specifications
| Physical Description | |
|---|---|
| Soft Clay Site – Onsøy |
The soils at the Onsøy site are marine clays. The engineering properties of the Onsøy clay site have previously been documented extensively (Gundersen et al. 2019). The natural water content varies between 45 and 65%. The average plasticity index varies from about 50 in the upper 9m to about 30 below 9m. The sensitivity (St) measured by fall cone tests is constant at about 6. The over-consolidation ratio (OCR) decreases from about 4 near the surface to 1.2 at 30 m depth. Such clays are found extensively in the Northern hemisphere, but also in Japan and southeast Asia. The Onsøy clay is also remarkably similar to clays found offshore at e.g. the Troll, Gjøa, Luva and Aasta Hansteen oil and gas fields. The similarities in characteristic and behaviour with many clays around the world illustrate the significance of the Onsøy deposit as a benchmark site.
|
| Quick Clay Site – Tiller |
Deposits of sensitive marine clay can be found over large areas of Scandinavia and north America. Such deposits are extremely challenging to work with for geotechnical engineers. In addition, landslides occur frequently due to both natural and man-induced triggers. The site at Tiller-Flotten is composed of homogenous marine clay, defined as quick (remoulded strength less than 0.5 kPa) from 7m below terrain and until a depth of 25m. The sensitivity (St) of the clay is about 150. A full overview of the site and data available is presented in L'Heureux et al. (2019).
|
| Silt Site – Halden |
The Halden silt site is located in southeastern Norway, approximately 120 km south of Oslo. The deposit consists of a uniform marine silt up to 10 m thick. Such intermediate soils are challenging materials in geotechnical design. The natural water content (w) in the silt decreases only slightly between depths of 4.5 to 11m, with values at about 30%. From 11 to 15m, the water content decreases more rapidly to about 21%. Soil classification charts suggest the Halden silt to be in the zones at the interface between "transitional soil" and "silt and low rigidity index ' Ir ' clays. Classification tests in the laboratory indicate a low plasticity silt with bulky grains. The clay content in the silt varies slightly from 9 to 15%. A full overview of the Halden silt site facility is presented in Blaker et al. (2019).
|
| Sand Site – Øysand |
The NGTS facility includes a site with loose to medium dense sand near Trondheim at Øysand. The glaciofluvial and deltaic deposit at this site is approximately 20-25 m thick, relatively homogenous, and consists mostly of fine to medium uniform sand with predominance of quartz minerals, some plagioclase and micas. A full overview of the sand site facility is presented in Quinteros et al. (2019).
|
| Permafrost Sites – Svalbard |
There are two permafrost sites available for testing in Longyearbyen on Svalbard (Gilbert et al. 2019). These sites are included within the NGTS infrastructure to investigate topics including foundation methodology, site investigation techniques, embankment behavior, and artificial cooling systems in saline marine clays and intermediate permafrost soils. These sites were selected as they are representative of the soil conditions in Svalbard and other Arctic locations. Access to both sites is easy as they are located close the the University research centre (UNIS) on Svalbard.
|
| Snow avalanche facility – Fonnbu/Ryggfonn | Fonnbu has, since its inception in 1973, been used for the collection of baseline data on weather and snow conditions, and for the monitoring of avalanches in the area. Fonnbu is located near the full-scale experimental avalanche facility, Ryggfonn, which is also located in the Grasdalen valley. Fonnbu is therefore used to accommodate personnel and serves as a starting point for field tests. Ryggfonn is one of the few full scale avalanche paths in the world instrumented for full scale experiments. The avalanche path in Ryggfonn has a vertical drop of 900 m and a total length of about 2100 m. The size of the avalanches usually varies from 2 (0.1 Gg) to 5 (100 Gg) measured in the Canadian classification for avalanche and the avalanche speed can reach up to 60 m/s. More information about the snow avalanche facility can be found here: https://www.ngi.no/eng/Services/Technical-expertise/Avalanches/Fonnbu. |
Image Gallery
