Conceptual design of floating drilling production and storage caisson for arctic waters

Gerwick, Ben C.; Jahns, H. O.

doi:10.1016/0141-0296(81)90016-x

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…It is clear, however, that horizontal resistance is significantly lower for a downward breaking cone. Gerwick and Jahns (1979) observed, from comparative tests, that the force on an upward breaking cone is 1.5-3 times greater than that for a downward breaking cone.…”

Section: Discussion Of Test Resultsmentioning

confidence: 99%

“…Ice-breaker supported drillships have also operated for almost five months of the year in deep-water areas of the same region. Production from these and other regions with even more severe ice conditions will, however, require new technology, and considerable effort is therefore being devoted to the development and evaluation of new concepts for offshore structures that will operate safely and economically under severe conditions (Jazrawi andKhanna 1978, Gerwick andJahns 1979). One such concept is a downward cone, which could be fitted to a cylindrical structure and operated in either a fixed or an oscillating mode.…”

Section: Introductionmentioning

confidence: 99%

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Model tests of ice forces on fixed and oscillating cones

Frederking

Schwarz

1982

Cold Regions Science and Technology

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science and Technology, 6, 1, pp. 61-72, 1982 Model tests of ice forces on fixed and oscillating cones Frederking, R. M. W.; Schwarz, J. Cold Regions

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Section: Discussion Of Test Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Model tests of ice forces on fixed and oscillating cones

Frederking

Schwarz

1982

Cold Regions Science and Technology

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“…A recent publication by Gerwick and Jahns [8] describes the conceptual design of a deep-water floating caisson vessel with a conicalshaped ice breaking surface. Their work included model tests from which they concluded that the downward-breaking mode effectively reduced the caisson's response by a factor between 1.5 and 3, compared to the upward-breaking mode.…”

Section: Oownward-breaking Conementioning

confidence: 99%

Plastic Limit Analysis of Sheet Ice Loads on Conical Structures

Ralston

1980

Physics and Mechanics of Ice

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The techniques of plastic limit analysis are used to develop a description of the forces imposed on conical-shaped structures by moving ice sheets. A closed-form solution is presented in which the relative importance of the essential features of the failure process can be clearly viewed. The behavior of broken ice pieces as they move around the surface of the cone is ~ important design consideration for upward-breaking conical structures. The form of the yield criterion used to describe ice bending strength is not a critical parameter. The large'ly one-dimensional nature of the ice bending activity near a conical structure does not require an accurate two-dimensional description of ice bending strength. Downward-breaking conical structures offer some advantages in the form of reduced horizontal loads compared to upward-breaking cones. This reduction is largely a consequence of the reduced forces needed to submerge broken ice pieces rather than push them up over the surface of an upward-breaking cone. Additional factors, such as the contribution of the vertical force to the overturning moment and the potential jamming of ice ridges against a downward-breaking cone in shallow water, should also be considered when downwardbreaking geometries are of interest. INTRODUCTIONPlastic limit analysis is a well-known approach for addressing questions of ultimate strength and plastic collapse in a number of engineering disciplines. Many applications can be found in the theory of plates and shells, concrete structures, frame analysis, geotechnical engineering, and rock mechanics. The simplicity of this approach permits the construction of approximate solutions to engineering problems without allowing minor details to obscure the essential features of the problem. The general procedure usually consists of constructing rigorous upper and lower bounds for the plastic failure load. Upper bounds are constructed with the use of assumed velocity fields that describe the motion that occurs in the failure process. Observations of actual material failures in model tests and full-scale events are very useful for selecting the

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“…It is generally recognized that the use of a conical structure at the waterline leads to reduced loads compared to a vertical sided structure such as a cylinder [3,4]. The reduction in loads is primarily due to different ice breaking modes -a conical structure induces flexural failure of the ice whereas vertical sided structures typically induce crushing failure.…”

Section: Introductionmentioning

confidence: 99%

Multi-Year Ice Model Tests on Caissons with Downward Breaking Cones

et al. 2011

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Some of the most promising concepts under evaluation for use as floating drilling platforms in Arctic offshore deepwater areas (water depth > 100 m) are floating caissons with downward breaking cones at the waterline. Model test results can be used to characterize loads under a variety of ice conditions to support development of platforms with high operability. This paper presents a test program conducted by ExxonMobil Upstream Research Company to characterize multi-year ice loads on floating caissons with downward breaking cones at the waterline. The experimental program investigated the dependence of ice loads on cone geometry, ice characteristics and ice drift speed, as well as the use of model test results to make reliable full scale predictions. One of the program's objectives was to characterize the reduction in ice loads due to the use of a downward breaking cone or when ice management is used to reduce floe size and concentration. As part of that, circumstances in which the use of a downward breaking cone or the presence of managed ice may not reduce loads as expected are highlighted. The intent in doing so is to provide insight on how to implement these load-reducing strategies most effectively.

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Conceptual design of floating drilling production and storage caisson for arctic waters

Cited by 3 publications

References 2 publications

Model tests of ice forces on fixed and oscillating cones

Model tests of ice forces on fixed and oscillating cones

Plastic Limit Analysis of Sheet Ice Loads on Conical Structures

Multi-Year Ice Model Tests on Caissons with Downward Breaking Cones

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