Global jack-up rig behaviour next to a footprint

Jun, Min; Kim, Y. H.; Hossain, Muhammad Shazzad; Cassidy, Mark; Hu, Yuxia; Park, S.G.

doi:10.1016/j.marstruc.2018.12.002

Cited by 15 publications

(3 citation statements)

References 34 publications

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“…Their research showed that the soil is obviously disturbed during the initial penetration and will recover with time. To simplify the problem, many of the following studies assumed an artificial footprint, such as Kong [13], Zhang et al [15], Jun et al [16][17][18][19]. The assumption of an artificial reverse cone footprint may respond to a fully recovered 'real' footprint after a long period from the initial penetration.…”

Section: Previous Workmentioning

confidence: 99%

Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

Zhang

et al. 2019

JMSE

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Most existing research on the stability of spudcans during reinstallation nearing footprints is based on centrifuge tests and theoretical analyses. In this study, the reinstallation of the flat base footing, fusimform spudcan footing and skirted footing near existing footprints are simulated using the coupled Eulerian–Lagrangian (CEL) method. The effects of footprints’ geometry, reinstallation eccentricity (0.25D–2.0D) and the roughness between spudcan and soil on the profiles of the vertical force, horizontal force and bending moment are discussed. The results show that the friction condition of the soil–footing interface has a significant effect on H profile but much less effect on M profile. The eccentricity ratio is a key factor to evaluate the H and M. The results show that the geometry shape of the footing also has certain effects on the V, H, and M profiles. The flat base footing gives the lowest peak value in H but largest in M, and the performances of the fusiform spudcan footing and the skirted footing are similar. From the view of the resultant forces, the skirted footing shows a certain potential in resisting the damage during reinstallation near existing footprints by comparing with commonly used fusiform spudcan footings. The bending moments on the leg–hull connection section of different leg length at certain offset distances are discussed.

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Section: Previous Workmentioning

confidence: 99%

Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

Zhang

et al. 2019

JMSE

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“…In addition, for mitigating spudcan-footprint interactions, a series of mitigating measures have been presented, including stomping [13], reaming [14], infi lling [15], successive leg repositioning [16], and water jetting with spudcan preloading [17]. However, the results of the above-mentioned measures have turned out to be either unsatisfactory or inconvenient and uneconomical [18]. Consequently, Hossain et al [3] and Jun et al [19] focused on adjusting spudcan structures to alleviate spudcan-footprint interactions and proposed a novel spudcan shape with a fl at base and 4 holes, which is based on the mechanism that the fl at base can reduce the induced horizontal force and holes can provide a preferential soil fl ow path to facilitate the spudcan penetrating vertically.…”

Section: Introductionmentioning

confidence: 99%

Research on Optimal Design of Spudcan Structures to Ease Spudcan-Footprint Interactions in Clay and Comparative Analyses with Different Measures

Yu¹,

Sun²,

et al. 2022

Polish Maritime Research

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In order to ease consequences of spudcan-footprint interactions during jack-up rigs reinstalling in the vicinity of an existing seabed footprint, three new types of spudcan shapes, that is, a lotus-shaped spudcan with six circular holes, a flat-bottomed spudcan, and a concave-shaped spudcan, were proposed to perform an optimizing study of the spudcan structures, and the effectiveness of them were analyzed comparatively with other different measures. Firstly, 3D Large Deformation Finite Element (LDFE) analyses were carried out using the Coupled Eulerian-Lagrangian (CEL) method in the commercial finite element package ABAQUS. After calibrating the validity of the numerical calculation model against existing centrifuge test data and LDFE results, the differences in interaction mechanism between the novel spudcans and the generic spindle-shaped spudcan were studied when penetrating near an existing footprint with an eccentric distance of 0.5D, and the horizontal range of plastic deformation of the disturbed soils, the inclination angle of the spudcan and the offset distance of the pile legs were analyzed comparatively as well. The results show that the proposed novel spudcans can mitigate the maximum horizontal sliding force and the maximum bending moment at the top of the pile leg obviously, compared with those of the generic one, which were reduced by 32.59%, 22.47%, 28.18%, and 26.32%, 12.88%, 18.02%, respectively. It also can be seen that all novel structures can ease the adverse consequences of spudcan-footprint interactions effectively, and can improve the in -place stability of the spudcan as well. Finally, three possible measures in mitigating interactions of the spudcan-footprint were contrasted, that is, the novel spudcan (represented by the lotus-shaped spudcan with six holes), stomping method, and perforation drilling method. The results show that all of them can reduce adverse impacts induced by interactions of the spudcan-footprint, and also can improve the in-place stability of the spudcan during reinstallation. In addition, among them, according to the effect of reducing the additional stress of the spudcan, the effectiveness of them can be listed as follows: perforation drilling near an existing footprint > the lotus-shaped spudcan with six holes > stomping method. In terms of the vertical bearing capacity of the spudcan, the lotus-shaped spudcan with six holes can improve it as much as 16.33% compared with the spindle-shaped structure due to the particularity of the structure. While reducing the continuity and strength of soil foundations, the perforation drilling measure leads to the decrease of the vertical bearing capacity of the spudcan by 13.07%. It can be concluded that all the three measures have merits and demerits, so the relevant construction environment conditions and engineering practice should be fully considered when selecting measures to deal with interactions of the spudcan-footprint.

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“…Furthermore, Zheng et al [13] numerically studied the spudcan-footprint interaction in non-uniform clay. Jun et al [14] used the numerical simulation method to study the global behavior of a jack-up unit close to a footprint.…”

Section: Introductionmentioning

confidence: 99%

Mitigation Effect of Perforation Drilling on the Sliding Risk during Spudcan Installation Close to Footprints

Gao

Liu

Shi

et al. 2020

JMSE

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Perforation drilling is a promising technique to mitigate the sliding risk of jack-up units installed around footprints. Based on the coupled Eulerian–Lagrangian (CEL) method, a 1/2 finite element model, including a rigid Lagrangian spudcan and a Eulerian soil part, was established, and the contact interface was modelled with the Coulomb friction model. Validated against an indoor perforation test, the model was adopted to investigate the mitigation mechanism and effects of the borehole diameter, number, depth, and the drilling range. The simulations reveal that the mitigation efficiency increases with the borehole diameter, number, and depth. However, it shows little improvement if the borehole depth increases beyond double footprint depth. The semi-drilling at the outer side of the footprint is a little more effective than the full-drilling at both the inner and outer sides of the footprint. The present work emphasizes the effects of perforation drilling parameters on the mitigation efficiency, which are of great significance to guide the engineering practice and guarantee the safe operation of the jack-up reinstallation close to existing footprints.

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Global jack-up rig behaviour next to a footprint

Cited by 15 publications

References 34 publications

Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

Research on Optimal Design of Spudcan Structures to Ease Spudcan-Footprint Interactions in Clay and Comparative Analyses with Different Measures

Mitigation Effect of Perforation Drilling on the Sliding Risk during Spudcan Installation Close to Footprints

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