Opportunities to improve the operational and technical management of jack-up deployments

Hunt, Rupert J.; Marsh, Philip

doi:10.1016/j.marstruc.2004.08.005

Cited by 40 publications

(15 citation statements)

References 3 publications

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“…The frequency of offshore incidents during installation near footprints has increased by a factor of four between the period 1979~1988 and 1996~2006 (Osborne 2005) and at an even higher rate over 2005~2012 (Jack et al 2013). Examples of incidents include (a) leg damage Perforation drilling for easing spudcan-footprint interaction issues Hossain & Stainforth Submitted January 2015, Revised November 2015 3 to the Mod V class Monitor and jack-up platforms in the Central North Sea (Hunt and Marsh 2004); (b) an exceptionally high RPD reading in the Starboard leg of a jack-up rig due to sliding towards the footprint (Handidjaja et al 2009); (c) some sliding was experienced by a rig installation as the legs were installed owing to the significantly different leg spacing from the previously installed L780-C Mod II unit (Brennan et al 2006).…”

Section: 'Mobile' Jack-up Rig and Spudcan-footprint Interaction Issuesmentioning

confidence: 99%

Perforation drilling for easing spudcan–footprint interaction issues

Hossain

Stainforth

2016

Ocean Engineering

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Section: 'Mobile' Jack-up Rig and Spudcan-footprint Interaction Issuesmentioning

confidence: 99%

Perforation drilling for easing spudcan–footprint interaction issues

Hossain

Stainforth

2016

Ocean Engineering

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“…Soil conditions of a thin layer of sand overlying a weaker stratum of clay are still proving hazardous during the installation of mobile jack-up platforms, with unexpected 'punch-through' failures continuing to be prevalent today (Hunt & Marsh, 2004). In spite of this awareness, assessment of spudcan penetration in sand over clay conditions is still based on methods developed from small-scale (laboratory floor) experiments of a size of footing that is much smaller than that of a modern day jack-up, which can exceed 20 m in diameter.…”

Section: Introductionmentioning

confidence: 99%

Revealing the bearing capacity mechanisms of a penetrating spudcan through sand overlying clay

et al. 2008

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The safe and economic use of mobile jack-up structures is still hindered by limited understanding of the installation of their large conical 'spudcan' footings in layered sand over clay sites. This paper addresses this by detailing experimentally observed bearing failure modes induced during the penetration of a spudcan through a layer of sand into underlying normally consolidated clay. Digital images were captured continuously by installing a half-spudcan against a transparent window, and analysed using a particle image velocimetry technique coupled with close-range photogrammetry correction. As the experiments were performed in a geotechnical centrifuge the observed mechanisms occurred in stress conditions of similar magnitude to the offshore case. The experimental evidence provides: (a) failure modes at different spudcan penetration depths; (b) the transitional failure mechanism at the event of peak bearing resistance; and (c) the changes in overall failure mechanism due to varying geometric and strength conditions of the layered soil. The results provide useful references for the development and validation of analytical or numerical solutions for this problem.

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“…Accident rates due to the effects of vibration and structural deficiencies remain comparatively high, making an accurate analysis of jack-up behaviors increasingly important. Recent attention has focused on understanding the behaviors of offshore platforms under dynamic loading conditions [4]. Jack-up platforms are flexible structures built to have natural periods of the same order as the predominant wave periods for many seas, which are designed based on structural modeling of the legs, analysis of the degree of flexibility provided by the spudcan, and assessment of the nature of the wave loads [5].…”

Section: Introductionmentioning

confidence: 99%

High Response Performance of a Tuned-Mass Damper for Vibration Suppression of Offshore Platform under Earthquake Loads

Zhao

Zheng

et al. 2016

Shock and Vibration

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Currently, tuned-mass dampers (TMDs) are widely applied to maintain the stability of offshore platforms in hostile environments; however, the stability system of offshore platforms faces considerable challenges under critical earthquake loads of the initial period. Therefore, this study concentrated on the high response performance of a simple passive TMD system, and numerical and experimental investigations were performed using a 1 : 200-scale prototype. The obtained results indicated that the displacement, acceleration, and their power spectral density all decreased significantly for the offshore platform with the TMD system. By further analyses of its high response characteristics, it was validated that the TMD reactions can commence within the first 3 s of earthquake excitation, while the fundamental natural frequency was consistently tuned for the TMD system dependent on the dynamic magnification factor. The evaluation indices also confirmed that this method is effective in reducing the overall vibration level and the maximum peak values of the offshore platform exposed to earthquake excitations, mainly because of its high response characteristics.

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Opportunities to improve the operational and technical management of jack-up deployments

Cited by 40 publications

References 3 publications

Perforation drilling for easing spudcan–footprint interaction issues

Perforation drilling for easing spudcan–footprint interaction issues

Revealing the bearing capacity mechanisms of a penetrating spudcan through sand overlying clay

High Response Performance of a Tuned-Mass Damper for Vibration Suppression of Offshore Platform under Earthquake Loads

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