Various phenomena occur under water during the operation of a sit-on-bottom type offshore structure settling on a sandy seabed. Scouring is one of such phenomena. It is a phenomenon that the seabed is scoured by the forces of waves and currents acting on the bottom of the structure and sand around and under the legs of the structure is carried away. This phenomenon causes local stress on the legs or collapse of the supporting ground due to shortage of soil mechanical supporting area, which sometimes leads to movement of the structure or even to its destruction. The authors conducted two kinds of studies: one is to create an effective bottom shape against scouring and the other concerns a method of quantitatively estimating the degree of scouring on an actual structure. In the first study, comparative tests were conducted on four types of models under the forces of waves, currents and their combined flows. In the second study, systematic tests were carried out on three types of square models of different sizes and four kinds of sand having different average grain sizes under the forces of current. As the result of these studies, it has become clear that a skirted hemispherical leg is most effective against scouring and a method of quantitatively estimating the degree of scouring on an actual structure has been developed.

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  • Corporate Authors:

    Mitsubishi Heavy Industries Limited

    5-1 Marunouchi, 2-chome, Chiyoda-Ku
    Tokyo 100,   Japan 
  • Authors:
    • Yatagai, K
    • Murase, Y
    • Tagya, K
  • Publication Date: 1973-2

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Filing Info

  • Accession Number: 00057188
  • Record Type: Publication
  • Source Agency: Mitsubishi Heavy Industries Limited
  • Files: TRIS
  • Created Date: Jul 31 1974 12:00AM