A study on ice loads during ice - structure interactions was started in 1993 by the Japan Ocean Industries Association (JOIA). Medium Scale Field Indentation Tests (MSFIT) were conducted during the winters of 1996 and 1997. The purpose of the tests was to investigate ice loads and ice failure characteristics, and to establish a new method of estimating ice loads during ice - structure interactions. The tests consisted of ice indentation tests, tests on physical properties of ice sheets, and measurements of ice sheet deformation. The test site was located at Futamigaoka Harbor on Lake Notoro, Hokkaido, whose entrance faces the Sea of Okhotsk. This paper describes the results of ice sheet strain measurements using strain gages and the estimation of strain area during ice/vertical-sided-structure interactions obtained during a winter test in 1997.
It is important to determine the design load on a structure to study how an ice sheet is destroyed, based on the parameters of structure width, ice thickness, and ice sheet indentation rate, during interaction between the structure and the ice sheet. A more rational design load can be determined if the ice sheets failure mode and the ice load can be estimated, based on the above three conditions. Ice load is known to be substantially influenced by the strain rate E. defined by the indentation rate and the ice sheet strain area. Therefore, It is necessary to evaluate the strain rate (strain area) to estimate the ice load and to evaluate the structure design load. Strain area has been measured in many laboratory experiments; however, this is difficult because of the limited experimental scale in the laboratory. Furthermore, many theories have been proposed for evaluating the strain propagation area, but no rational theory has yet been established.
