Norwegian Geotechnical Institute (NGI) Digital Archive
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New CPT methods for evaluation of the axial capacity of driven piles
Get PDFHigh costs associated with offshore foundation installations have provided strong impetus to the offshore energy sector in the search for more reliable design methods. This paper provides a summary of an Industry sponsored project that led to the development of new CPT-based design methods for the evaluation of the axial capacity of driven piles. Particular attention was given to the need for the new methods to be applicable to large diameter offshore piles given that many existing methods are derived by calibration with capacities measured in static pile load tests on smaller diameter onshore piles. The basic mechanisms supporting the general format of the expressions proposed for shaft friction and end bearing in sands and clays are described. It is shown how the new expressions, which are calibrated against a database of the most reliable load tests reported in the literature, lead to better predictions of capacity compared to other methods and can also satisfactorily predict the capacity of piles driven into deposits comprising interbedded layers of sand, silt and clay. Recommendations for the prediction of pile displacements at working loads using CPT data are also presented.New CPT methods for evaluation of the axial capacity of driven pilespublishedVersio
Feathers as an integrated measure of organohalogen contamination, its dietary sources and corticosterone in nestlings of a terrestrial bird of prey, the northern Goshawk (Accipiter gentilis)
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Getting in control of persistent, mobile and toxic (PMT) and very persistent and very mobile (vPvM) substances to protect water resources: strategies from diverse perspectives
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The Fate and Transport of Chlorinated Polyfluorinated Ether Sulfonates and Other PFAS through Industrial Wastewater Treatment Facilities in China
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The Sensitivity of Tsunami Impact to Earthquake Source Parameters and Manning Friction in High-Resolution Inundation Simulations
Get PDFIn seismically active regions with variable dominant focal mechanisms, there is considerable tsunami inundation height uncertainty. Basic earthquake source parameters such as dip, strike, and rake affect significantly the tsunamigenic potential and the tsunami directivity. Tsunami inundation is also sensitive to other properties such as bottom friction. Despite their importance, sensitivity to these basic parameters is surprisingly sparsely studied in literature. We perform suites of systematic parameter searches to investigate the sensitivity of inundation at the towns of Catania and Siracusa on Sicily to changes both in the earthquake source parameters and the Manning friction. The inundation is modelled using the Tsunami-HySEA shallow water code on a system of nested topo-bathymetric grids with a finest spatial resolution of 10 m. This GPU-based model, with significant HPC resources, allows us to perform large numbers of high-resolution tsunami simulations. We analyze the variability of different hydrodynamic parameters due to large earthquakes with uniform slip at different locations, focal depth, and different source parameters. We consider sources both near the coastline, in which significant near-shore co-seismic deformation occurs, and offshore, where near-shore co-seismic deformation is negligible. For distant offshore earthquake sources, we see systematic and intuitive changes in the inundation with changes in strike, dip, rake, and depth. For near-shore sources, the dependency is far more complicated and co-determined by both the source mechanisms and the coastal morphology. The sensitivity studies provide directions on how to resolve the source discretization to optimize the number of sources in Probabilistic Tsunami Hazard Analysis, and they demonstrate a need for a far finer discretization of local sources than for more distant sources. For a small number of earthquake sources, we study systematically the inundation as a function of the Manning coefficient. The sensitivity of the inundation to this parameter varies greatly for different earthquake sources and topo-bathymetry at the coastline of interest. The friction greatly affects the velocities and momentum flux and to a lesser but still significant extent the inundation distance from the coastline. An understanding of all these dependencies is needed to better quantify the hazard when source complexity increases.publishedVersio
Cyclic Capacity of Monopiles in Sand under Partially Drained Conditions: A Numerical Approach
Get PDFCyclic loading of saturated sand under partially drained conditions may lead to accumulated strains, pore pressure buildup, and consequently reduced effective stress, stiffness, and shear strength. This will affect the ultimate limit state capacity of monopile foundations in sand for offshore wind turbines. This paper calculates the performance of large-diameter monopile foundations, which are installed in uniform dense sand, subjected to storm loading using the partially drained cyclic accumulation model (PDCAM). The simultaneous pore pressure accumulation and dissipation is accounted for by fully coupled pore water flow and stress equilibrium (consolidation) finite element analyses. Drainage and cyclic load effects on monopile behavior are studied by comparing the PDCAM simulation results with simulation results using a hardening soil model with small strain stiffness. At the end, a simplified procedure of PDCAM, named PDCAM-S, is proposed, and the results using this approach together with PLAXIS 3D and the NGI-ADP soil model are compared with the PDCAM results.Cyclic Capacity of Monopiles in Sand under Partially Drained Conditions: A Numerical ApproachacceptedVersio
Influence of initial microcracks on the dynamic mechanical characteristics of sandstone
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H1.1 Klimapåvirkning
Get PDFDagens klima representerer en utfordring for veier i Norge, og klimaendringene vil ytterligere øke disse utfordringene. Spesielt vil økning i nedbør, både årsnedbør og hyppighet og intensitet av ekstremhendelser, ha en særlig påvirkning på naturfarer som truer veier og annen infrastruktur. Prosjektet Klimavei skal etablere et kunnskaps-grunnlag for å gjøre samfunnsøkonomiske analyser på prosjekt- og systemnivå som tar hensyn til forventninger om endringer i klima og klimapolitikk, i tillegg til å bidra til at man når mål om trygghet, bærekraft og effektivitet i vegsektoren. Rapporten beskriver grunnlaget for bruk at de klimaelementene som er i endring. Utviklingen i de viktigste klimaelementene er gitt med utgangspunkt i framskrivninger for Norge frem til år 2100. Deretter beskrives enkeltvis primære (klimaelementene direkte) og sekundere prosesser som ulike skredtyper. Informasjon om effektene for ulike deler av veisektoren samles for relevante klima- og naturfareelementer.
Gjennomgangen viser at det ofte er et tett samspill mellom ulike direkte og indirekte prosesser som til slutt fører til konsekvenser for veinettet og transportsektoren. For eksempel kan kortere snøsesong og mindre snø føre til mindre beskyttelse av jords-monnet mot store mengder regn om vinteren slik at erosjon kan igjen føre til jord- og flomskred. Slike komplekse prosesser er som regel stedsspesifikke. For analysen av konkrete veiprosjekter vil derfor scenarier være en metode for å inkludere kompleksi-teten i de involverte prosessene.Norges forskningsrådpublishedVersio