Norwegian Geotechnical Institute (NGI) Digital Archive
Not a member yet
1356 research outputs found
Sort by
Discovery of Holocene ooid shoals in a siliciclastic delta, De Grey River, North West Shelf, Australia
Get PDFOnshore and offshore site investigations along the dryland tide-dominated De Grey River delta (northwestern Australia) led to the unexpected discovery of the largest yet-known marine ooid shoals in the Indo-Pacific region. Ooids exhibit up to 60 tangential aragonitic laminae that were formed around fluvial sediment grains during the late Holocene. Covering an area >1250 km2, their spatial extent rivals in size individual ooid shoals from the Bahamas. Shoals appear to be spatially linked with the De Grey River, suggesting that fluvial outputs, combined with a macrotidal range, facilitated the precipitation of the ooids. Following their formation, ooids were reworked through tidal and wave processes along the delta. As a result, the delta sedimentary features, including beach ridges, mouth bars, and distributary channels, are composed of ooids. This discovery broadens the range of depositional and climatic environments in which ooids can form and demonstrates that fluvial runoff may not inhibit aragonite precipitation. Such a configuration also provides a unique analogue for ancient ooids found in association with siliciclastic grains and further indicates that the interpretation of typical siliciclastic geomorphologies from geophysical data does not preclude the presence of carbonate grains.Discovery of Holocene ooid shoals in a siliciclastic delta, De Grey River, North West Shelf, AustraliapublishedVersio
Lateral behavior of monopiles in sand under monotonic loading: Insights and a new simple design model
Get PDFpublishedVersio
Validation of earthquake analysis methodology of a suction-caisson foundation-structure through model testing
Get PDFpublishedVersio
A physics-inspired machine learning approach for water-tightness estimation of defective cut-off walls with random construction errors
Get PDFpublishedVersio
WP1 - Mixed fractions of black shale and rhomb porphyry
No full textWhen taking out potentially acid-producing black shale in construction projects, rock masses are often unintentionally mixed with masses of other rocks. The acid-producing potential of such mixed masses is uncertain, and as a result, large amounts of potentially clean rocks often end up in disposal sites. In WP1 of the Under Oslo project, the leaching from mixed masses with different fractions of rhomb porphyry with black shale has been investigated. Both dilution and additional buffering effects of the rhomb porphyry are assumed to contribute to the desired effects.
To investigate this hypothesis, both small scale column experiments, as well as larger scale outdoor container experiments have been conducted over the course of two years. Different amounts of black shale have been mixed with rhomb porphyry in both experiments. Additionally, for the column experiments, the effect of grain size has been investigated. While the outdoor container experiments have been exposed to ambient conditions, with varying precipitation, humidity and temperature, the column experiments are executed under more ideal laboratory conditions, with regular watering and more stable atmospheric conditions. The columns and most containers are free drainage systems, where the system is unsaturated with water and with dry periods. Some containers are closed and water-saturated; however, these are not covered in this report.
This document describes the results two years into the experiments. Additionally, one specific case related to construction of is described, where mixed fractions of syenite and black shale were analysed to evaluate an appropriate threshold for when rock masses should be deposited in appropriate landfills.Norges forskningsrå
Quantifying the effects of nature-based solutions in reducing risks from hydrometeorological hazards: Examples from Europe
Get PDFpublishedVersio
Electrochemical Oxidation for Treatment of PFAS in Contaminated Water and Fractionated Foam─A Pilot-Scale Study
Get PDFpublishedVersio
First geophysical investigations to study a fragile Pomor cultural heritage site at Russekeila – Kapp Linné), Svalbard
Get PDFWith climate warming, the cultural heritage sites of the Arctic are in great danger. Extensive research is needed to study such sites. The archaeological site at Russekeila – Kapp Linné, Svalbard was selected for the survey as previous research had highlighted its vulnerability to cryospheric hazards. The main objectives of the survey were (i) to register the precise surface and subsurface locations of cultural heritage (CH) (remains of an 18th century Russian Pomor trapper's hut) objects within the study area, (ii) to determine the impact of coastal erosion on the CH objects and (iii) to understand the near-surface stratigraphy of the site. The geophysical surveys were carried out using a Ground Penetrating Radar (GPR) instrument with two shielded antennas of 500 MHz and 800 MHz centre frequencies. Only weak anomalies were observed at the intersections with wooden drifts, which can be explained by the low contrast between the relative dielectric constant values of the driftwood and the background soil. The depth extent of the driftwood within the soil was understood from the processed GPR data to a depth of approximately 25 cm. A near-surface stratigraphy of the site morphology, including thaw depth, saturated and unsaturated sediments and soil cover, was established based on multiple reflectors observed to 2 m depth. Loose sediments are indicated by reflectors to a depth of approximately 20 cm. Unsaturated fine sediments, which show a stronger signal compared to the underlying saturated sand layers, can be observed from about 1.2 m depth. No reflectors are shown below the thaw depth.First geophysical investigations to study a fragile Pomor cultural heritage site at Russekeila – Kapp Linné), SvalbardpublishedVersio
