Loads on an Off-Shore Structure due to an Ice Floe Impact

• Autorzy: Staroszczyk R.
• Języki publikacji: EN

Abstrakty

EN

In the paper, the problem of dynamic impact of a floating ice sheet at an off-shore structure is considered. It is assumed that during an interaction event the dominant mechanism is the brittle fracture of ice at the ice--structure interface, that is, elastic and creep effects in ice are ignored. Since in natural conditions the edge of floating ice is usually irregular, the contact between a floe and an engineering object is imperfect. Thus, at any one time, the failure of ice occurs only in a number of small zones along a structure wall, leading to a highly irregular variation of forces exerted on the structure during the impact process. It is supposed in the analysis that the successive small-scale fracture events at the contact surface occur at random, and all these small-scale events take place independently of each other. An off-shore structure is modelled as a fixed and rigid circular cylinder with vertical walls. For an adopted geometry of the ice sheet, its initial horizontal velocity, and the variety of parameters describing the limit failure stresses in ice, the history of total loads sustained by the structure and the floe velocity variation are illustrated for a typical impact event. Furthermore, probability distributions for maximum impact forces exerted on the structure, depending on the floe size, its thickness and initial velocity, are determined.

Słowa kluczowe

EN

floating ice; offshore structure; dynamic impact; brittle fracture

• Wydawca: Institute of Hydro-Engineering of Polish Academy of Sciences
• Czasopismo: Archives of Hydro-Engineering and Environmental Mechanics
• Rocznik: 2007
• Tom: Vol. 54, nr 2
• Strony: 77--94
• Opis fizyczny: Bibliogr. 21 poz., il.

Twórcy

autor

Staroszczyk R.

• Institute of Hydro-Engineering, Polish Academy of Sciences, ul. Waryńskiego17, 71-310 Szczecin, Poland,

Bibliografia

• 1. Ashby M. F., Hallam S. D. (1986), The failure of brittle solids containing small cracks under compressive stress-states, Acta Metall., 34 (3), 497–510.
• 2. Hawkes I., Mellor M. (1972), Deformation and fracture of ice under uniaxial stress, J. Glaciol., 11 (61), 103–131.
• 3. Hibler W. D. (1979), A dynamic thermodynamic sea ice model, J. Phys. Oceanogr., 9 (4), 815–846.
• 4. Iliescu D., Schulson E. M. (2002), Brittle compressive failure of ice: monotonic versus cyclic loading, Acta Mater., 50 (8), 2163–2172.
• 5. Ip C. F., Hibler W. D., Flato G. M. (1991), On the effect of rheology on seasonal sea-ice simulations, Ann. Glaciol. 15, 17–25.
• 6. Jordaan I. J. (2001), Mechanics of ice–structure interaction, Eng. Fract. Mech., 68 (17-18), 1923–1960.
• 7. Kamio Z., Matsushita H., Strnadel B. (2003), Statistical analysis of ice fracture characteristics, Eng. Fract. Mech., 70 (15), 2075–2088.
• 8. Kim J., Shyam Sunder S. (1997), Statistical effects on the evolution of compliance and compressive fracture stress of ice, Cold Reg. Sci. Technol., 26 (2), 137–152.
• 9. Morland L. W., Staroszczyk R. (1998), A material coordinate treatment of the sea-ice dynamics equations, Proc. R. Soc. Lond., A 454 (1979), 2819–2857.
• 10. Nixon W. A. (1996), Wing crack models of the brittle compressive failure of ice, Cold Reg. Sci. Technol., 24 (1), 41–55.
• 11. Overland J. E., Pease C. H. (1988), Modeling ice dynamics of coastal seas, J. Geophys. Res., 93 (C12), 15,619–15,637.
• 12. Palmer A. C., Sanderson T. J. O. (1991), Fractal crushing of ice and brittle solids, Proc. R. Soc. Lond., A 433, 469–477.
• 13. Pralong A., Hutter K., Funk M. (2006), Anisotropic damage mechanics for viscoelastic ice, Continuum Mech. Thermodyn., 17 (5), 387–408.
• 14. Sanderson T. J. O. (1988), Ice Mechanics. Risks to Offshore Structures. Graham and Trotman, London.
• 15. Schulson E. M., Gratz E. T. (1999), The brittle compressive failure of orthotropic ice under triaxial loading, Acta Mater., 47 (3), 745–755.
• 16. Sjölind S. G. (1987), A constitutive model for ice as a damaging visco-elastic material, Cold Reg. Sci. Technol., 14 (3), 247–262.
• 17. Smith R. B. (1983), A note on the constitutive law for sea ice, J. Glaciol., 29 (101), 191–195.
• 18. Staroszczyk R. (2005), Loads exerted by floating ice on a cylindrical structure, Arch. Hydroeng. Environ. Mech., 52 (1), 39–58.
• 19. Staroszczyk R. (2006), Loads exerted on a cylindrical structure by floating ice modelled as a viscous-plastic material, Arch. Hydroeng. Environ. Mech., 53 (2), 105–126.
• 20. Tremblay L. B. (1999), A comparison study between two visco-plastic sea-ice models, [in:] Advances in Cold-Region Thermal Engineering and Sciences (eds. K. Hutter, Y. Wang and H. Beer), pp. 333–352, Springer, Berlin.
• 21. Xu Y., Xu J., Wang J. (2004), Fractal model for size effect on ice failure strength, Cold Reg. Sci. Technol., 40 (1–2), 135–144.