The ice shear failure results from the interaction of the ice sheet with vertical offshore structures. The sea ice was treated as a Coulomb-Mohr material in conducted investigations. It was obtained that the shear stresses increased with the normal stress increase according to a linear law. With further normal stress increase an angle of internal friction changes. The loading rate have an influence on the angle of internal friction. The sea ice cohesion depends on temperature. The results of the research work were compared with the data obtained before.
The estimation of ice force on offshore structures Is connected with the determination ice strength in front of the structure. The lee strength has to satisfy the strength criteria which correspond to the characteristic features of ice influence to the ice failure mechanizm and to the properties of sea ice as a material. Among the wide-spread failure criteria the Coulomb-Mohr criterion is one which is in good agreement with the test results. It differs from other strength criteria with its generality and allows to foresee both the probability of brittle failure without large deformations and the material transmation from elastic state to ductile. This criterion accounts for the mechanism of shear failure. The results of shear strength investigation of coastal sea ice were presented in the works of Zanegin and Khrapaty (1975, 1976). Then the study was carried out for model ice in the form of granular material (Prodanovic,1979; Weiss et al,1981). Later the shear strength of a drift ice sheet (Zanegln, 1984) and of model granular ice in different scales (Hellman.1984; Frasson and Sandkvist,1985) was studied.
The samples of coastal and drift ice sheets in Japanese and Okhotsk Seas were taken for test.
