CONCEPTUAL MODELING THE SYSTEM FOR ENSURING DESIGN RELIABILITY OF THE OFFSHORE ICE-RESISTANT HYDRAULIC STRUCTURES BASES

The phenomenon of vibration is considered in the paper. A serious threat to the safety of stationary marine structures operating in conditions of ice fields drift, is the vibration that occurs during cutting of the ice cover by the supports of structures. The process of interaction, as an object of research, is described by the force of resistance to a change in equilibrium in the formed natural-man-made “ice field - structure” system, simultaneously affecting both the edge of the ice field and the base of the structure, and growing to a certain maximum, then “dumped” to a certain minimum. The moment of the beginning of ice destruction is due to the achievement of the critical density of elastic energy accumulated in the compressed local volume of ice in the contact zone, which is the trigger of ice load phenomenon release on the structure and the beginning of its return to the equilibrium state, i. e. is the source of its oscillations. Such cyclic destruction of ice, as the main subprocess in the complex process of interaction between the ice field and the structure, must be viewed as a subject of research, since this phenomenon reflects the real mechanism of transforming the kinetic energy of the ice field movement into the potential specific energy of the newly formed surfaces of the destroyed fragments of ice. As a methodological basis and a tool of scientific research, the system analysis is used in the work as a method of setting and solving the problem through the decomposition of the process under study, analysis of its constituent phenomena and synthesis of an adequate model of cyclic ice destruction to study unsolved problems in calculating the loads of ice fields on offshore free-standing structures. The characteristics of the cyclic process of ice destruction, both the values of ice load peaks and their frequency are the initial parameters when performing a dynamic calculation of the structure to determine its reliability level. Obtaining these characteristics is possible only when using the energy criterion of ice destruction, the type and location in the design system of which are defined in the work.

marine hydraulic structures, vibration, sea ice, ice destruction, cyclic load, system approach, specific energy of destruction

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