SAMCoT - Annual Report 2015

SAMC

• ANNUAL REPORT 2015

Ice rubble

Sergey Kulyakhtin and Anna Pustogvar, about to submit

their PhDs Thesis, and Post–Doc Arttu Polojärvi,,

currently appointed Assistant Professor of Ice Mechanics

at the Department of Applied Mechanics at the Aalto

University’s School of Engineering, have been working on

ice rubble through experimental, analytical and numerical

approaches.

Pustogvar` s research focuses on determining a standard

methodology for sea ice density measurements. Although

ice density is widely used for solving engineering and

geophysical problems no standard methodology exists

when it comes to sea ice. Based on the laboratory tests

performed at UNIS in 2015 and field tests performed in

2013 during OATRC2013 WP2 researchers compared the

most common mass/volume and hydrostatic weighing

methods. The results showed that the hydrostatic weighing

is currently the best available method for measuring sea

ice density. Figure WP2_2 shows the spread is significantly

lower for the hydrostatic weighing than for the traditional

mass/volume approach

Ice rubble macroporosity is another vital parameter, and

up to date most values derive from 1D drilling. However,

drilling gives insight only on linear representation of poros-

ity. In cold laboratory of NTNU we performed ice rubble

packing tests in order to understand if 3D macroporos-

ity differs from the porosity obtained by drilling (Figures

WP2_3, WP2_4 & WP2_5). With the laboratory results

WP2 researchers verified an analytical model of ice rubble

macroporosity. This model operates with ice fragment

gradation curves as the main input which can be obtained

from observational studies of ice fragments in ice ridges.

Figure WP2_2 Sea ice density profile of a core sampled, March

Van Mijen Fjord, Spitsbergen; The density - mass/volume (MV)

and hydrostatic weighing (HW) methods

Figures WP2_3 Test set-up for the ice rubble packing experiments: 1 – packing table, 2 – guiding plank, 3 – plexiglass cylinder filled

with saline water, 4 – ice rubble & Figure WP2_4 An example of ice rubble packing test performed in the cold laboratory at NTNU

Figure WP2_5 Results of ice production for monodisperse ice fragment packings