Norwegian Geotechnical Institute (NGI) Digital Archive
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A Hybrid Methodology of Rock Support Design for Poor Ground Conditions in Hard Rock Tunnelling
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Drilling 1100-km-long seafloor ridges reveals how palaeoshorelines control carbonate shelf morphologies (North West Shelf, Australia)
Get PDFThe Rowley Shelf, the southern half of the tropical, carbonate-dominated, North West Shelf of Australia, is covered with linear ridges that can be tracked parallel to the coast over 1100 km between the modern coast and the 140 m isobath. Here, we investigate the origin and nature of these ridges based on the integration of extensive borehole data, high-resolution geophysical data, age dating and compaction analysis. Our investigation reveals that each ridge consists of now-submerged relict coastal deposits that were formed over the last 200,000 years through wave, tidal, fluvial and aeolian processes. These features were dominantly preserved through early diagenesis and illustrate the longest continuous submerged palaeoshorelines reported to date. The distribution of relict coastal features, and therefore early diagenesis, controls the morphology of the continental shelf. First, relict coastal features tend to be stacked on top of each other, resulting in the formation of composite diachronous coastal deposits that form distinctive steps on the seabed, up to 10s m high. Second, relict coastal features form a hard substrate that controls the location of coral reefs along the shelf. Reefs, including a 20-m-thick MIS 3 drowned coral reef described here for the first time, as well as modern reefs of the Muiron Islands, Montebello Islands and Dampier Archipelago, are all developed on top of relict coastal features. The distribution, size and mineralogy of relict coastal features highlight climatic changes along the Rowley Shelf. High relative sea levels (RSL) are associated with low carbonate production and up to 50% of terrigenous grains, while low RSL deposits exhibit increased carbonate production and reduced terrigenous grain content. This asymmetry is interpreted to reflect the onset of the monsoon associated with increased fluvial runoffs during interglacial periods. Lastly, our work shows that compaction analyses are critical for palaeoenvironment and RSL reconstructions. Indeed, the accumulation of 50 m of sediment on a RSL indicator can result in an offset of the measurement by 12.7 m.Drilling 1100-km-long seafloor ridges reveals how palaeoshorelines control carbonate shelf morphologies (North West Shelf, Australia)publishedVersio
Assessment of the impact of pile driving on slope stability
Get PDFDriving piles near slopes can be challenging in terms of temporarily reducing slope stability, specifically in the presence of sensitive clay or lenses of sand and silt in the ground. There is currently no standard method for calculating the reduced safety factor of a slope due to pile driving, even though this has been the initiating cause for a few landslides in the Nordic countries, Canada, and the United States, among others. This paper investigates some of these cases of slope failure, looks into the possible failure mechanisms and assesses the traditional methods used to calculate the reduced factor of safety of the slope during pile driving. Finally, the paper provides suggestions for better evaluation of pile driving effects on slope stability based on the results of numerical analyses in Plaxis 2D Geotechnical finite element package, coupled with soil mechanics theory and project experience.Assessment of the impact of pile driving on slope stabilitypublishedVersio
Container experiments yearly report 2022
Get PDFContainer experiments investigating leaching from alum shale under different conditions were started autumn 2020 as a part of the Under Oslo project at NGI (SP13). Furthermore, leaching from alum shale mixed with different amounts of rhomb porphyry was investigated, giving a total of 14 containers. The black shale in these containers were taken out from a road cut by E16 at Kleggerud autumn 2020. Additionally, 5 containers set up by the Norwegian Public Road Authorities (Statens vegvesen, SVV) in 2014 and 2015 to investigate leaching from alum shale and Galgeberg shale originating from the construction of the tunnel at Gran, Rv. 4, were taken over by NGI and measurements of leachate quality were resumed in November 2020. Autumn 2021 another two containers from SVV were taken over by NGI.Norges forskningsrå
Environmental impact assessments of geotechnical works
No full textOne of the major contributors to global carbon emissions is the construction sector. Using world environmental input-output tables from 2009, the total CO2-emissions from the global construction sector was calculated to account for 23% to total emissions, of which 94% were related to indirect emissions (Huang et al., 2018). Direct carbon emissions are emissions at the construction site and are related to burning of gasoline, diesel, and other petroleum products, while indirect carbon emissions are related to emissions caused by raw material extraction and manufacturing of materials. Work package 4 (WP4) of the project Under Oslo focused on quantifying the environmental impact of geotechnical works using life cycle assessment (LCA). There is currently a lack of standardization of when calculating environmental impacts from geotechnical works using LCAs, and for reporting of results from impact calculation (e.g., Kendall et al. (2018), Samuelsson et al. (2021)). This report provides an overview of the work carried out in the work package 4 (WP4) of the project Under Oslo with the focus on "environmental impact assessments". A summary and discussion of different documents prepared in this work package is given,
after which future research is suggested.Norges forskningsrå
Stabilisation of Soft Clay, Quick Clay and Peat by Industrial By-Products and Biochars
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Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation
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