Basic HTML Version
40
SAMC
o
T
• ANNUAL REPORT 2013
formation of radial and cleavage cracks with nominal
pressure up to 3.5 MPa.
Coastoal ice and water action
Ice pressure cells Geokon were installed on the walls
of the cofferdam (Figure 24) in the coal quay Kapp
Amsterdam to register ice loads caused by large
deformations of the cofferdam over 10 years. Four
ice pressure of cells were installed on the frontal and
lateral walls the cofferdam. A highest ice pressure of
0.5 MPa was registered in the end of April – beginning of
May on the lateral wall of the cofferdam. This is where
the largest deformations are observed. Maximal ice
pressure was repeated with semidiurnal frequency and
associated with temperature changes in the top layer of
the ice (Figure 24a). Semidiurnal temperature variations
are related to the migration of sea water through the
confined ice inside the cofferdam under the influence of
tide induced under ice water pressure (Figure 26b). The
effect was reproduced in the ice tank in the cold labora-
tory at UNIS. In this tank, the Faber Bragg Grating strain
and temperature sensors were used to register both
ice temperature variations and deformation of the tank
wall induced by variations of under ice water pressure
(Marchenko et al., 2013). Experiments on thermal
expansion of saline ice were performed in the cold
laboratories at UNIS and University College of London.
Variations of ice pressure with semidiurnal period were
also registered near the boundary of floating ice and ice
foot frozen to the shoreline in Svea (Wrangborg et al.,
2013). In this case, ice stresses are caused by mechani-
cal deformations of ice cover over the fjord from low
water phase when the ice partially is grounded to high
water phase when the ice is floating.
a) b)
Figure 25. Ice pressure cells and thermistor string installed on the walls of the cofferdam (a). Uploading of the data in May
2013 (b).
a) b)
Figure 26. Synchronous semidiurnal variations of the ice pressure and ice temperature at 25 cm depth (a), records of the
ice temperature at depths 5, 15, 25 and 35 cm.