Field indentation tests using medium scale model structures have been conducted since the winter of 1996. Model structures 4.5 and 6.0m wide were used, and sea ice was up to 27cm thick in the 1997 winter tests. The purpose of this study was to understand the ice failure mechanisms at the ice-structure interface, e.g. the ice failure mode, simultaneous versus non-simultaneous ice failure, size of independent ice failure zone and its influencing factors, etc. This paper presents a summary of the 1997 winter tests.
The Japan Ocean Industries Association (JOIA) started a five-year program, "A Study of Ice Load Acting on Offshore Structures" (Heads of the committee: Prof. Hiroshi Saeki of Hokkaido University and Prof. Ken-ichi Hirayama of Iwate University) in 1993, as an enterprise assigned by the Ministry of International Trade and Industry (MITI). It is known that indentation ice pressure decreases with increasing indentation area. The purpose of this medium-scale field indentation test was to investigate the relationship between indentation ice pressure and indentation area, and to determine if this trend is due to the non-simultaneous ice sheet failure. In the 1996 winter tests, the authors conducted an indentation test with indentor widths of 1.5 and 3.0m and ice thicknesses of 6 to 24cm. The test results were presented in the ISOPE in 1997 (Takeuchi et aI, 1997). In the 1997 winter, tests were conducted with indentor widths of 4.5 and 6.0m and ice thicknesses of 12 to 24cm. The test conditions are listed in Table 1 for both the 1996 and the 1997 winter test series. The tests were conducted inside the harbor of Notoro fishing port, Notoro Lake, Hokkaido, which is connected to the sea of Okhotsk. The test site location is shown in Fig.1.
