Norwegian Geotechnical Institute (NGI) Digital Archive
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Effects of fines content in numerical simulation of CPTu in silty sands
Get PDFThe Cone Penetration Test (CPTu) does not measure soil properties directly; rather, it measures cone resistance, sleeve friction and pore water pressure, that correlated with laboratory test data, allow estimation of soil properties. These correlations work reasonably well in clean sand; however, they have been observed to provide poor estimation when fines are present. The aim of this work is to improve the estimation of fine contents in silty sands from CPTu measurements. Large deformation finite element analyses in ABAQUS implicit scheme with the "zipper technique" is used to simulate CPTu. The SANISAND model is used to capture the soil behaviour and account for fines content by altering the critical state line. Coupled consolidation analyses are performed to account for development of pore pressures during cone penetration. The influence of fines and drainage on the tip resistance and developed pore pressure is analysed. Existing field CPTu measurements would be back calculated using laboratory test data, to ascertain the accuracy of the developed framework. The results are analysed in tandem to improve the understanding of effect of fines content on CPTu response.publishedVersio
Accounting for effects of cyclic loading in design of offshore wind turbine foundations
Get PDFIn the design of foundations for offshore structures, it is generally important and required to consider the effects of cyclic loading caused by waves and wind. Therefore, NGI has developed a framework since the early 1970s that has been utilized in the design of various offshore structures. However, there are currently no accepted guidelines on how to account for this effect in design of monopile foundations. With the introduction of large-diameter monopile foundations for offshore wind turbines, it has become necessary to revisit and modify our existing procedure. The primary difference between monopile foundations for offshore wind turbines and those for the oil and gas industry is that the design of the former is typically not governed by a global failure mechanism during extreme storm loading because of their rather ductile response. Additionally, offshore wind parks often consist of over one hundred turbines, which necessitates more efficient design methods to optimise each individual foundation within a huge field with varying soil stratigraphy. This paper presents an efficient procedure using the finite element method to account for the effects of cyclic loading in design of monopile foundations. Furthermore, it provides recommendations for further improvements.publishedVersio
Seabed structures and foundations related to deep-sea resource development: A review based on design and research
Get PDFThe deep‐sea ground contains a huge amount of energy and mineral resources, forexample, oil, gas, and minerals. Various infrastructures such asfloatingstructures, seabed structures, and foundations have been developed to exploitthese resources. The seabed structures and foundations can be mainly classifiedinto three types: subsea production structures, offshore pipelines, and anchors.This study reviewed the development, installation, and operation of theseinfrastructures, including their structures, design, installation, marine environ-ment loads, and applications. On this basis, the research gaps and further researchdirections were explored through this literature review. First, differentfloatingstructures were briefly analyzed and reviewed to introduce the design require-ments of the seabed structures and foundations. Second, the subsea productionstructures, including subsea manifolds and their foundations, were reviewed anddiscussed. Third, the basic characteristics and design methods of deep‐seapipelines, including subsea pipelines and risers, were analyzed and reviewed.Finally, the installation and bearing capacity of deep‐sea subsea anchors andseabed trench influence on the anchor were reviewed. Through the review, it wasfound that marine environment conditions are the key inputs for any offshorestructure design. The fabrication, installation, and operation of infrastructuresshould carefully consider the marine loads and geological conditions. Differentstructures have their own mechanical problems. The fatigue and stability ofpipelines mainly depend on the soil‐structure interaction. Anchor selection shouldconsider soil types and possible trench formation. These focuses and researchgaps can provide a helpful guide on further research, installation, and operationof deep‐sea structures and foundationsSeabed structures and foundations related to deep-sea resource development: A review based on design and researchpublishedVersio
APALI – Avalanche Probability Along Linear Infrastructure
Get PDFTo secure linear infrastructure in the most cost-efficient manner, hazard hot-spots need to be known not only with regard to the intensity of possible events but also their probability. Traditional hazard mapping methods rely on analysis of historical records—which are often missing or scarce—or on experts’ subjective judgment. Either approach is timeconsuming and expensive. The hazard mapping system NAKSIN for snow avalanches contains a module for estimating avalanche release probability automatically using topographical, weather and forest data and calculates avalanche run-out for one target return period. This Note outlines how NAKSIN can be modified to produce maps of avalanche hit probability and optionally probability distribution functions of impact pressure and/or flow velocity. While the needed modifications are easy to implement, the NAKSIN module for release probability requires improvements to produce more reliable estimates in areas with continental climate.Research Council of Norwa
Assessing potential building damage caused by leakage to urban tunnels
Get PDFBuilding damage is a major risk for urban tunnelling. In areas with soft soil conditions, water ingress to bedrock tunnels can cause significant pore pressure reduction, consolidation settle-ments and damage to nearby buildings and infrastructure. In Norway, guidelines to determine leakage limits are based on a national database, containing data on water ingress, pore pressure reduction and influence zone. To support future projects, the database has been implemented into an ArcGIS-tool and merged with the Ground Impact and Building Vulnerability (GIBV) method to assess potential building damage at early project stages. This paper presents the adopted methodology and shows its application for a new subway tunnel in Oslo, Norway.Assessing potential building damage caused by leakage to urban tunnelsacceptedVersio
Recycling of paper, cardboard and its PFAS in Norway
Get PDFPer- and polyfluoroalkyl substances (PFAS) have been used in paper products since the 1960s. PFAS emissions during the life cycle of these products have been substantial sources of these substances to the environment. Here, a total of 37 PFAS were analysed in 13 paper products sampled in 2021, for which some were made of virgin paper and others recycled paper, including food contact materials (FCM), packaging, and a notebook. In addition, different fractions of the recycling process of corrugated paper and board were sampled at a Norwegian cardboard recycling plant and analysed for the same PFAS, to get an overview of PFAS in the recycling stream of these materials in Norway. PFAS were found in recycled paper and board, indicating PFAS can be a non-intentionally added substance (NIAS) in recycled paper products. Sum of targeted PFAS detected in paper products (including products made of virgin and recycled materials) ranged between 0.4 and 971 µg kg−1, dominated by SAmPAP diester and 6:2 FTS (0–62% and 0–98%, respectively). The sum of targeted PFAS in returned corrugated paper and board in Norway is at least 32 kg per year (6 mg per capita per year). Recycling is important to ensure sustainability. As part of the broad PFAS restriction in Europe, PFAS are to be restricted in paper and board materials. Thus, lower levels of PFAS entering the recycling stream are expected in the future. Monitoring is necessary to assess reductions of PFAS in the paper waste stream due to PFAS regulations in Europe.Recycling of paper, cardboard and its PFAS in NorwaypublishedVersio
New development of sprayed concrete with improved waterproofing, durability and sustainability performance
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