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Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
Blikra - vajont 2013
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Blikra - vajont 2013

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International Conference Vajont2013 - 8 October

International Conference Vajont2013 - 8 October

Published in: Technology, Business
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  • 1. DMS DMS Lars Harald Blikra & Lene Kristensen, Åknes/Tafjord Monitoring Centre Mario Lovisolo, Centro Servizi di Geoingegneria (CSG), Italy Åknes/Tafjord Beredskap IKS
  • 2. Risk related to large rockslides in Norway Åknes Tafjord 1934 Loen 1905 og 1936 Åknes/Tafjord Beredskap IKS
  • 3. Monitored rockslides in Norway Handled by two monitoring centres funded by government/NVE, municipalities and counties: • Åknes/Tafjord Beredskap (technical and geological) • Nordnorsk fjellovervåking (technical) Åknes/Tafjord Beredskap IKS CONTENT  Requirements  Subsurface investigations & instrumentation  Åknes and Jettan case  Conclusions
  • 4. Regulations in Norwegain building code • The population safety needs to be taken care of by realtime monitoring, warning and evacuation • The warning time shall not be shorter than 72 hours and the evacuation time shall be maximum 12 hours • A system for daily continuous monitoring of the conditions, e.g. by measurements of displacements • Independent monitoring instruments and backup communication and power systems • Sufficient technical and geo personnel/competence for safe and reliable monitoring and warning Åknes/Tafjord Beredskap IKS
  • 5. (1) Investigations • Surface • Subsurface (2) Monitoring systems • Surface • Subsurface • Driving mechanisms Åknes/Tafjord Beredskap IKS
  • 6.     Geophysics were possible Core drillings Borehole logging – televiewer and other sensors Borehole displacements Åknes/Tafjord Beredskap IKS
  • 7. INSTRUMENTATION Inclinometer probe – manual readings ? Long columns with continuous records Considerations • • • • • Åknes/Tafjord Beredskap IKS High cost of boreholes Robustness Characterization vs real-time warning Resolution Flexibility
  • 8. • Robust technology • Leading technology • Large economic savings in a long-term perspective The DMS borehole instrumentation: • Documented to have survived more than 70 cm movements Conventional methods: c. 3 cm Åknes/Tafjord Beredskap IKS DMS
  • 9. Casing Åknes/Tafjord Beredskap IKS
  • 10. Method: Differential monitoring system (DMS) 1 m modules Åknes/Tafjord Beredskap IKS
  • 11. Differential monitoring system, DMS – “Snake” Real-time , continuous measurements Steel modules with sensors Flexible centralizers fixed to the borehole casing Flexible junctions Åknes/Tafjord Beredskap IKS Subsurface LAB: • 2D Inclinometer (0,4 mm resolution) • Pietzometer • Temperature sensor • Digital compass • One systems of 150 m length, total of 304 sensors
  • 12. Example: Åknes Deep drillings Åknes/Tafjord Beredskap IKS
  • 13. SEE ALSO POSTER: GB INSAR MEASUREMENT AT THE ÅKNES ROCKSLIDE, NORWAY Åknes/Tafjord Beredskap IKS
  • 14. Åknes/Tafjord Beredskap IKS
  • 15. Deep core drillings – 200 m deep Åknes/Tafjord Beredskap IKS
  • 16. N E Televiewer image of the sliding plane Sliding zone Åknes/Tafjord Beredskap IKS S W N
  • 17. 2 years of displacements 2011and 2012: Direction towards SW Sliding plane 2009 - 2013: • Total of 9 cm movements on 2 sensors Åknes/Tafjord Beredskap IKS Accumulated total Differential Movement for each individual sensor
  • 18. DMS time series: 49-51 m depth Åknes/Tafjord Beredskap IKS
  • 19. Åknes/Tafjord Beredskap IKS
  • 20. Time line for sensor at 49-50 m depth. • Displacement • Water level • Temperature Internal changes/ dynamics of the rockslide controls the hydrological system and the deformations Åknes/Tafjord Beredskap IKS
  • 21. Lyngseidet Åknes/Tafjord Beredskap IKS
  • 22. Aktive back fracture: 20-25 m deep, 2,5 cm/year Åknes/Tafjord Beredskap IKS
  • 23. Active movements Åknes/Tafjord Beredskap IKS
  • 24. Depth/Size/Volume? Åknes/Tafjord Beredskap IKS
  • 25. Rock cores Åknes/Tafjord Beredskap IKS
  • 26. Clay in sliding zone: 45 m depth Åknes/Tafjord Beredskap IKS
  • 27. Borehole instrumentation to measure movements, temperature and water Åknes/Tafjord Beredskap IKS
  • 28. DMS movements at 45/46 m depth: 1th of May – 3rd of October E Åknes/Tafjord Beredskap IKS
  • 29. Time series February – August 2013 May 2013 Åknes/Tafjord Beredskap IKS
  • 30. Active movements Åknes/Tafjord Beredskap IKS
  • 31. Volume: Probably 5-6 mill. m3 Åknes/Tafjord Beredskap IKS
  • 32. DMS and Real-time warning • Each sensor have threshold values for displacements • Can follow directly the critical sliding zones • Sms thresholds: 1 mm/day • Threshold values for different hazard levels • Trustable and robust system • Little noise compared to surface measurements Åknes/Tafjord Beredskap IKS
  • 33.  Norwegian building codes has strong requirements for monitoring and permanent handling of the EWS  Subsurface data gives a knowledge platform for early-warning and key data for geological models/volumes needed for evaluation of runout/tsunamis (RISK)  Borehole instrumentation is a vital part of real-time monitoring  DMS instrumentation is a robust in-situ laboratorium: • Direct displacement at sliding planes with directions • Water pressure vs movements • Temperature/permafrost vs movements Åknes/Tafjord Beredskap IKS
  • 34. Important that the geoscientific community clearly tells the government what knowledge is needed for reliable monitoring and EW Åknes/Tafjord Beredskap IKS

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