Recently there are some oil/gas fields which are being developed in the North-Eastern part of Sakhalin Island where ice drift velocity achieves 1.5 m/sec. High dynamics of ice cover and its considerable thickness cause higher requirements to reliability of off-shore ice-resistant platforms (IRP). Problem of how to estimate design reliability of means designed to develop offshore fields in the northern seas is connected with development of methods of how to determine ice effects and how to implement dynamic design calculation of structures for ice load effects, with investigation of marine ice as substance, and with mechanism of creation of ice regime and of structure loading regime. Authors suggested a model of mechanical interaction between ice and IRP. The model is based on numerical simulation of the process when ice cover affects the structure. The suggested model may determine following parameters of mechanical interaction between ice cover and a structure: quantity of load cycles, time of penetration, depth of penetration, and regime of ice load to structure.
Ice loads on marine ice-resistant platforms (IRP) depend on a plenty of factors, are random and, hence, it is expedient to describe them by methods of probability theory and the theory of stochastic functions. To define probable characteristics of such process it is expedient to assess its parameters in various time scales. In long-term or seasonal scales variability of ice loading is defined by variability of ice mode parameters in water areas. In scale, which is commensurable to the period of IRP variations, variability of ice loading is defined by complex interaction between ice cover and IRP. Thus, to describe ice loading it is necessary to consider variability of ice mode parameters and process of ice destruction (when interacting with IRP) at the same time (Timokhov et al, 1987).