Norwegian Geotechnical Institute (NGI) Digital Archive
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Deliverable 3.2 Stress and burial history impact on present day state
No full textThis report documents the work done in WP3.2-Stress and burial history impact on present day state. From existing databases, literature data and dedicated rock deformation experiments we have analysed, developed, and tested empirical relationships of K0, permeability and consolidation parameters vs. stress loading and unloading. The analysis in this report is based on a wide range of datasets applicable for North Sea sedimentary systems including new tests and data from Horda platform and analogues for Endurance site. The results and methodology have general applications, and examples of the relevance are shown for mature Horda Platform area and for the less mature Lisa (DK) at the end of report. This work is input to WP1.2 and 1.3 and are closely linked to DV1.2 report, where, this report documents the experimental testing and empirical relationships.European CommissionpublishedVersio
Deliverable 1.3: Accounting for Stress History and Lithology through Forward Geomechanical Modelling
No full textA core theme of the SHARP project is integrating the stress history of the North Sea basins into stress characterisation and experimental testing procedures, and by extension developing an appreciation for how this might influence assessment of risk and monitoring requirements for storage operations. The link here is geomechanical modelling, which facilitates predictions of subsurface deformation as a function of evolving stress conditions and the experimentally constrained constitutive properties. This report documents a suite of geomechanical models applied to the Horda platform area of northern North Sea. Evolutionary models of the Troll area are presented, with specific focus on well 31/6-1, which examine the significance of burial history, chemical compaction and uplift/glaciation on stress and pore pressure in the area. When explicitly representing these processes and leveraging understanding of mineralogical significance developed in earlier tasks it is found that these support log-based workflows presented in Deliverable 1.2. Conclusions regarding the probable causes for elevated shallow stresses and pore pressures at these sites are made. Preliminary efforts to direct the procedures and techniques to the Smeaheia alpha well 32/4-1 are shown.
The key findings of the modelling work are summarised and implications for risk and monitoring are presented. Concepts for extending the work within 3D geomechanical models are provided and will be tackled in subsequent project tasks.European CommissionpublishedVersio
Durability of geogrid reinforcement from a sloped retaining wall after 25 years in-service
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NAKSIN 4 - dokumentasjon
Get PDFNGI har på oppdrag av NVE utviklet en metodikk for å beregne Nye AktsomhetsKart for Snøskred I Norge (NAKSIN). Bakgrunnen var at eksisterende aktsomhetskart fra 2010 var for konservative i mange områder da de ikke tar hensyn til skog og klima, mens de på den andre siden ikke fanger opp særlig lange utløp i høyfjellet og i områder med kontinentalt klima og lave friksjonsverdier.
NAKSIN-modellen er et Python-rammeverk som tar hensyn til skog i både utløsnings-områder og utløpsberegning, klima i beregning av utløsningssannsynlighet, for deretter å kjøre en dynamisk modell med klima- og terrengavhengige friksjonsparametere for hvert enkelt skredløp. Summen av alle skredutløp gir til sammen et nytt aktsomhetskart for Norge.
NAKSIN er kjørt både med og uten skogseffekt for hele Norges fastland. Resultatet er vektorbaserte utløsningsområder og aktsomhetskart, hvor en rekke attributter er tilgjeng-elige for hvert enkelt utløsningsområde. Aktsomhetskart produsert med NAKSIN med skogseffekt dekker et areal tilsvarende eksisterende aktsomhetskart fra 2010, mens antall bygg i sikkerhetsklasse S2 og S3 som ligger innenfor aktsomhetssonene er halvert.Norges vassdrags- og energidirektorat (NVE
Analysis, occurrence and removal efficiencies of organophosphate flame retardants (OPFRs) in sludge undergoing anaerobic digestion followed by diverse thermal treatments
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Tracking aftershock sequences using empirical matched field processing
Get PDFExtensive aftershock sequences present a significant problem to seismological data centres attempting to produce near real-time comprehensive seismic event bulletins. An elevated number of events to process and poorer performance of automatic phase association algorithms can lead to large delays in processing and a greatly increased human workload. Global monitoring is often performed using seismic array stations at considerable distances from the events involved. Empirical matched field processing (EMFP) is a narrow-frequency band array signal processing technique that recognizes the inter-sensor phase and amplitude relations associated with wavefronts approaching a sensor array from a given direction. We demonstrate that EMFP, using a template obtained from the first P arrival from the main shock alone, can efficiently detect and identify P arrivals on that array from subsequent events in the aftershock zone with exceptionally few false alarms (signals from other sources). The empirical wavefield template encodes all the narrow-band phase and amplitude relations observed for the main shock signal. These relations are also often robust and repeatable characteristics of signals from nearby events. The EMFP detection statistic compares the phase and amplitude relations at a given time in the incoming data stream with those for the template and is sensitive to very short-duration signals with the required characteristics. Significant deviations from the plane-wavefront model that typically degrade the performance of standard beamforming techniques can enhance signal characterization using EMFP. Waveform correlation techniques typically perform poorly for aftershocks from large earthquakes due to the distances between hypocentres and the wide range of event magnitudes and source mechanisms. EMFP on remote seismic arrays mitigates these difficulties; the narrow-band nature of the procedure makes arrival identification less sensitive to the signals’ temporal form and spectral content. The empirical steering vectors derived for the main shock P arrival can reduce the frequency dependency of the slowness vector estimates. This property helps us to automatically screen out arrivals from outside of the aftershock zone. Standard array processing pipelines could be enhanced by including both plane-wave and empirical matched field steering vectors. This would maintain present capability for the plane-wave steering vectors and provide increased sensitivity and resolution for those sources for which we have empirical calibrations.Tracking aftershock sequences using empirical matched field processingacceptedVersio
Building information modelling based ground modelling for tunnel projects – Tunnel Angath/Austria
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Transformative adaptation through nature-based solutions: a comparative case study analysis in China, Italy, and Germany
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Extreme precipitation on dry ground in western Norway – characteristics of induced landslides call for adaptation of the Norwegian practice in landuse planning
Get PDFFollowing a particularly dry summer, a torrential rain event struck Western Norway on Tuesday 30 July 2019. The resulting floods and shallow landslides caused one fatality and severe damages to public and private infrastructure in the former Jølster municipality. Building on earlier work, in which we identified characteristics of the shallow landslides induced by torrential rains on unsaturated soils, we here present suggestions for adaptation of the Norwegian practice in landuse planning.publishedVersio
