Sea Ice Engineering

Journal of the Korean Society of Marine Engineering, 2013

Analysis of scenarios of transportation oil and gas which produced in the Arctic and others cold seas shows that in the near-term there will be a significant increase of tonnage of tankers for oil and gas and number of ships which should be exploited in difficult ice conditions. For the construction of ice-resistant structures (IRS) intended for production of oil and gas and transportation of these products at ice-class vessels, calculating the load from ice to board the ship and on surface of supports of the platforms are the actuality and urgent tasks. These tasks have one basis in both cases: at beginning of the contact occurs fracture of edge of ice, then occurs compressing of rubble shattered of ice, then they extruding from contact area, after this next layer of ice begin to destruct. At calculating the strength of plating and elements construct of vessels, icebreakers and ice-resistant platforms the specific energy of mechanical destruction ice   is an important parameter. For the whole period of study of physical and mechanical characteristics of sea ice have been not many experimental studies various researchers to obtain numerical values of this energetic characteristic of the strength of ice by a method called Ball Drop Test. This study shows that the destruction of the ice from dynamic loading in zone of contact occurs in several cycles, and the ice destructed with a minimum numerical values of  . The author offer this energy characteristic to take as a base value for the calculation of ice load on ships and offshore structures.

ASCE Proceedings of the Specialty Conference, Civil Engineering in the Oceans IV

Civil Engineering in the Oceans: Icebreaker Experience as a Guide to Sea Ice Forces on Structures

Power technology and engineering, 2016

Problems and potential approaches to determining ice characteristics for sea hydroengineering structures design are considered. A system for numerical modeling of ice dynamics is presented. The system may be used to define ice characteristics on approaches to structures with due regard for local hydrometeorological conditions and ice loads on structures. System application examples are presented for determining computational scenarios for ice loads at structures of the Pevek floating nuclear power plant (FNPP), as well as for the breakwater pier under reconstruction in Vanino. A scenario approach is used to determined ice loads.

ASCE Civil Engineering in the OCEANS IV Vol. II , 1978

ICEBREAKER EXPERIENCE AS A GUIDE TO SEA ICE FORCES ON STRUCTURES Ben C. Gerwick Jr.1 , F.ASCE & Lawrence B. Karp2 , M.ASCE ABSTRACT The design and verification of fixed platforms for Arctic and sub-Arctic ocean service requires a determination of the probable sea ice forces acting on structures of various configurations and sizes. Considerable research, including field measurements and model testing, has been carried out over past years. By necessity, almost all of this has been performed in micro-scale, and adaptation of that data to the scale of actual structures requires use of relatively large correction factors. Until there has been a significant history of fixed structures in sea ice, a promising source of data appears to be use of icebreaker vessel experience. Because icebreaker vessels traverse a varied sequence of sheet and ridge forms, they integrate the forces that may be imposed on a fixed structure over a period of time. In order to translate such data from a moving ship to a fixed structure, it is necessary to evaluate characteristic ice failure mechanisms of each. An energy approach based on a three dimensional failure criterion offers a practicable means for correlation and resolution of icebreaker data into the several components involved, and hence determination of total forces acting on fixed structures.

2014

Thesis presents new upwards bending icebreaking (UBIB-) process and hull form. The development of the process is based on theory which includes studies of sea ice physical properties and precedent studies of icebreaking resistance components, both in full and in model scale. The presented compilation of sea ice theory and ice measurement reports reveal that ice bending strength decreases significantly when the direction of bending is changed from downwards to upwards. This reduction of strength is strongly related to temperature gradient through the ice thickness. The theory of UBIB process and basic equations for calculating the ice resistance in level ice conditions is introduced. The theory relies on existing formulations and data of icebreaking process resistance components. New and adapted resistance components are formulated using simple physical approaches. The ice model tests, made with the developed UBIB model, confirmed the basic functioning of the hull type. The tests also introduced new challenges in modelling due to the model ice properties. The behaviour of the model ice in icebreaking velocity changes from brittle to plastic when the bending direction is changed. The theory presented in this thesis predicts over 60% decrease of ice resistance in level ice conditions, when new hull type is compared to the current state of the art.

A review of the technical literature concerning ship/ice interaction is presented. The context of the review is a joint Canada-Finland research project (JRPA No.5) to study ship interaction with actual ice. The constituents of ship/ice interaction are described. The literature concerning six ship/ice interaction scenarios is examined in detail. The six scenarios are; ramming a thick ice edge, impact with a single floe, contact with a thin ice edge, level icebreaking, ridge transit, and pack ice transit. Application of the technology to actual conditions is discussed, including ice load measurements and transit and risk simulations. The source and nature of randomness in ice loads is discussed. Directions for research are proposed.

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences

Records of the ice pressures on the joggle skirt of the coal quay in Spitsbergen were performed over winter seasons in 2013 and 2015. The ice thickness below the quay was above 2 m. Ice temperature over the ice thickness and water pressure at the sea bed were measured synchronously. It was discovered that sea water migrates through the ice confined inside the joggle skirt under the influence of tidal changes of the water pressure below the ice. It leads to the formation of floods on the ice surface during high tide. The ice surface becomes dry during low tide. Ice temperature and ice pressure on the joggle skirt are changed according to the semidiurnal cycle. Spectral analysis and correlation analysis are performed to analyse the loads caused by thermal expansion of the ice. A thermo-mechanical model of ice based on elastic-plastic rheology with thermal effect is used in numerical simulations of the observed phenomena. Numerical simulations are performed with finite element software...

The paper presents studies of the energy characteristic of sea ice strength   , which does adequately account for physical properties and process of its failure at a dynamic indentation a solid body in it. The mathematical model depicting the process of sea ice failure after contact with a body surface is proposed. The model is grounded on assumptions of the cyclic process of layer-by-layer failure of a half-space from ice at an indentation a rigid body into it. The results of experimental studies are reduced, which one have affirmed a hypothesis about cyclic nature of the failure process of ice block on interface. It was shown, that the magnitude   can be considered as constant magnitude for sea ice and can be used in load calculations on offshore structures as the ice strength characteristic.

2015

Recently some oil/gas fields 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 offshore ice-resistant platforms (IRP). The problem of estimation of design reliability of structure for development of offshore fields in northern seas is connected with development of methods of ice effects’ determination and implementation of 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 pene...