MARINE SOIL MECHANICS. APPLICATIONS TO NORTH SEA OFFSHORE

Some of the more important aspects of offshore foundation engineering are reviewed. Geophysical survey consists of continuous profiling, echo sounding for the bottom survey and boomer and sparker profiling for detecting the depth of the different reflectors. For shallow sampling, the simplest equipment is a grab which extracts surface material from the sea floor. The use of the gravity type sampler and the free fall device are also described. Deep boring from special ships equipped with a centerwell is outlined. Work is in progress on a hydraulically operated wireline sampler to be used inside the drill string. The most valuable in-situ testing has been the core penetration test. The details of soil investigation program are outlined. Soil conditions(water depths, geology)in the North Sea are briefly described. Piles for template structures are designed for large capacitites. Two types of piles (1) inserted pile and (2) a pile with enlarged footing are illustrated. Foundation problems related to offshore gravity structures are listed and discussed. Details are given of the installation platforms, settlement, the displacement due to static load from a 100-year wave, and the effect of cyclic loading. Comments are made on the dynamic analysis and vibration, scour, instrumentation of gravity platforms, and the required safety factors. Calculated and measured settlement of the Ekofisk oil storage tank are illustrated. The settlement calculations are based on finite element analysis with assumed soil conditions. Vital subjects for further research are noted.

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  • Supplemental Notes:
    • Lecture presented at "Offshore North Sea" Technology Conference and Exhibition, Stavanger, 3-6 September 1974.
  • Corporate Authors:

    Norwegian Geotechnical Institute

    P.O. Box 40 Tasen
    Oslo 8,   Norway 
  • Authors:
    • EIDE, O
  • Publication Date: 1974

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  • Accession Number: 00095908
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 2 1975 12:00AM