ABSTRACT
A certain number of cracks of various origins are present during the organization of work and movement on the fast ice. During sea level fluctuations, the tidal cracks appear parallel to the coast or encircling ice formations, with grounded icebergs and grounded hummocks. Rather broad cracks form during fast ice movements. The abrupt changes of air temperature, cleaning of ice surface from thick snow layer can be accompanied by thermal cracks. The cracks of technogenic origin appear during loading of ice, hydrostatic disequilibrium of snowice cover and other impacts on ice from the side of vessels and vehicles. Some cracks are dangerous for vehicles and people because of reduced ice-load bearing capacity, while a large number of visually observable cracks allow to cross them without any restrictions. The experience of ice-technological work performance and cargo transportation along fast ice in case of cracks presence in the ice cover is summarized in the report. To estimate the degree of ice strength decrease after cracks congelation in the ice basin of the Krylov Research Centre in Saint-Petersburg, a set of laboratory experiments was performed to estimate the ice bending strength of the congealed cracks and unbroken ice under the conditions of various water salinity and ice formed from it. The estimations of ice breccias strength relative to the strength of unbroken ice of primary structure were obtained.
Fast ice is a form of stationary ice, nevertheless it faces dynamic impacts, which result in deformations of ice cover and forming cracks. Tide cracks, which occur due to vertical movements of ice cover during sea level fluctuations, represent a characteristic feature of the sea fast ice. Besides tide cracks, in fast ice there are cracks formed as a result of horizontal shears, thermodynamic processes in ice cover, natural and anthropogenic loads on ice cover.
