Model Ice Preparation
The tests on model ice were performed in the Ice basin of the Krylov State Research
Centre in St. Petersburg, Russia, with dimensions 35.0 m × 6.0 m × 1.8 m.
1
Two types of model ice were used in the tests: (1) FG model ice with the granular
structure, and (2) columnar model ice with a thin top layer of granular structure and
main layer of the columnar structure. These model ice types reveal various
behaviors under identical loading. The ice basin of the Krylov Centre is capable to
generate both types of model ice to suit best specific experimental purposes.
The procedure for preparation of fine granule (FG) ice is as follows: a service
carriage is running forward and back in a cold room (ambient air temperature is
about −20 °C) spraying droplets of brine freezing in the air, which are settling as
fine grains layer by layer on the water surface. The spraying is continued until the
required ice thickness is reached. The advantage of the FG model ice is that the
flexural bending strength of ice can be reproduced in a rather wide range with a
close elasticity modulus to flexural strength ratio, which is characteristic of the
natural sea ice. Among shortcomings of this method are low values of crushing and
compression strength of the model ice (lower than that required according to the
similarity criterion) as well as the absence of brittle fracture in some loading
conditions.
Unlike the FG ice, the columnar ice is prepared by seeding ice crystals on the
water surface to form crystallization nuclei with further growth of vertical columnar
crystals at low air temperature. As a rule, this type of model ice is characterized by
relatively high compressive strength, which allows brittle failure of ice, but often
the ratio between the flexural and compressive strengths and modulus of ice elasticity are different from the full scale field values and, therefore, ice failure patterns
do not reproduce the actual processes.
Description of the Test Procedure and the Equipment
In both full-scale and model ice tests two parallel cuts were made in the ice cover to
obtain an ice beam with fixed ends (Fig. 2). The distance between these cuts w is
roughly equal to the ice thickness, while the beam length in different tests varied
approximately from 2 to 8 ice thickness. A horizontal force was applied at the
mid-length of the ice beam normally to the beam side. Vertical indenters were used
in these experiments: in the full scale tests it was a semi-cylinder indenter with a
diameter of 0.15 m, while in the ice basin it was a cylinder indenter of 0.02 m
diameter. The indenters were high enough to ensure that the load was applied across
the entire ice thickness by the horizontal displacement of the vertical indenter.
1
The basin has been demounted in 2014.
594
M. Karulina et al.
The tests on model ice were performed in the Ice basin of the Krylov State Research
Centre in St. Petersburg, Russia, with dimensions 35.0 m × 6.0 m × 1.8 m.
1
Two types of model ice were used in the tests: (1) FG model ice with the granular
structure, and (2) columnar model ice with a thin top layer of granular structure and
main layer of the columnar structure. These model ice types reveal various
behaviors under identical loading. The ice basin of the Krylov Centre is capable to
generate both types of model ice to suit best specific experimental purposes.
The procedure for preparation of fine granule (FG) ice is as follows: a service
carriage is running forward and back in a cold room (ambient air temperature is
about −20 °C) spraying droplets of brine freezing in the air, which are settling as
fine grains layer by layer on the water surface. The spraying is continued until the
required ice thickness is reached. The advantage of the FG model ice is that the
flexural bending strength of ice can be reproduced in a rather wide range with a
close elasticity modulus to flexural strength ratio, which is characteristic of the
natural sea ice. Among shortcomings of this method are low values of crushing and
compression strength of the model ice (lower than that required according to the
similarity criterion) as well as the absence of brittle fracture in some loading
conditions.
Unlike the FG ice, the columnar ice is prepared by seeding ice crystals on the
water surface to form crystallization nuclei with further growth of vertical columnar
crystals at low air temperature. As a rule, this type of model ice is characterized by
relatively high compressive strength, which allows brittle failure of ice, but often
the ratio between the flexural and compressive strengths and modulus of ice elasticity are different from the full scale field values and, therefore, ice failure patterns
do not reproduce the actual processes.
Description of the Test Procedure and the Equipment
In both full-scale and model ice tests two parallel cuts were made in the ice cover to
obtain an ice beam with fixed ends (Fig. 2). The distance between these cuts w is
roughly equal to the ice thickness, while the beam length in different tests varied
approximately from 2 to 8 ice thickness. A horizontal force was applied at the
mid-length of the ice beam normally to the beam side. Vertical indenters were used
in these experiments: in the full scale tests it was a semi-cylinder indenter with a
diameter of 0.15 m, while in the ice basin it was a cylinder indenter of 0.02 m
diameter. The indenters were high enough to ensure that the load was applied across
the entire ice thickness by the horizontal displacement of the vertical indenter.
1
The basin has been demounted in 2014.
594
M. Karulina et al.