MODEL AND FIELD EXPERIMENTS FOR DEVELOPMENT OF ICE RESISTANT OFFSHORE STRUCTURES

In order to meet the demand for offshore oil development in the Sub-arctic and Arctic, Mitsui Engineering & Shipbuilding Co., Ltd. has conducted research to establish technology to predict the ice loads applied on various shapes of ice resistant structures as a basis for designing optimum structures. The ice force measuring experiments have included laboratory tests performed by Arctec Inc., U.S.A., outdoor tests using medium size models in a lagoon and field tests on a large size tower specially installed in the Okhotsk Sea. This large tower was built in August 1976, 600 m off Mombetsu in Hokkaido at a water depth of 6.5 m and had a cylindrical shape of 9.5 m in height and 2.5 m in diameter. This tower was converted the next year to a conically shaped structure of 11 m in height and 5.5 m diameter at the water line. In winter the site was covered with pack ice ranging from 30 to 60 cm in thickness. The ice loads were sensed by measuring bending strains at the tower root and transmitted through sub-sea cable to land, and observations of ice behavior around the tower were conducted. Model tests of a mono-cone, mono-pod, four-legged conical structures, and four-legged cylindrical structures were conducted in an ice model basin of Arctec Inc. These were tested in unconsolidated and semiconsolidated first-year pressure ridges and rafted ice. Also, outdoor tests have been conducted at the Saroma Lagoon near Mombetsu since 1976 using medium sized models on various types of ice-resistant structures. The phenomena of vibratory crushing were also investigated. In this paper the outline of these tests including the correlation of ice loads on cone-shaped structure between the different tests is presented as well as some design consideration for ice-resistant structures.

Media Info

  • Features: References;
  • Pagination: p. 307-314

Subject/Index Terms

Filing Info

  • Accession Number: 00329928
  • Record Type: Publication
  • Report/Paper Numbers: Volume 4 Proceeding
  • Files: TRIS
  • Created Date: Apr 15 1981 12:00AM