In the study, the problems of a statistical modeling of ice loads from drifting hummocky features and level ice fields on the reinforced gravity based structures in Piltun-Astohsky and Lunsky fields offshore Sakhalin are investigated. The authors made a comparative analysis of ice loads on various types of gravity based structures in conditions of the Sea of Okhotsk according to the standards, procedures and guidelines from various codes of design. And also the probabilistic model of ice loads, developed by the authors in the previous studies, was considered for comparative analysis.
Practical realization of oil and gas projects in the Far East has started with "Sakhalin I" and "Sakhalin II" Projects under which four reinforced- concrete gravity producing platforms, like "Orlan" ("Sakhalin I"), "Piltun-Astohsky-A" (PA-A or "Molikpaq"), "Piltun-Astohsky-B" (PA-B) and "Lunsky-A" (LUN-A) ("Sakhalin II") were built on 30-50 m depths. Nevertheless, to provide reliability, safety and to decrease risk of operation of similar structures remain a problem till now. Durability and reliability of the ice-resistant structures depends on validity of calculation of the ice loads from ice features of a various age and nature (such as drifting level ice fields, the hummocky and rafting fields, separate hummocks of large size, grounded hummocks, etc.). Thereupon the problem of comprehensive study of ice impacts and development of methods of calculation of ice loads on the offshore hydroengineering structures remains urgent in world practice for more than one decade. The existing design codes from USA and Canada (API, 1995; CSA, 2004; ISO, 2007), and also some other countries, are grounded on experience of design and exploitation of fixed platforms for environmental conditions of Cook Inlet, the Beaufort Sea and Bohai Bay, where platforms of pile type and gravity-based concrete structures were applied.