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

Gao, Pan; Liu, Zhihui; Shi, Danda; Fu, Xuehua; Yan, Keliang

doi:10.3390/jmse8020118

Cited by 3 publications

(1 citation statement)

References 18 publications

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“…In this section, the eccentric distance of 0.5D was taken as the fi nal position to reinstall the spudcan near an existing conical footprint as described earlier as well. Based on the numbers of drilling holes, diameter and depth of boreholes set in the research of foundation drilling modeled by Pan et al [33], the soil foundation near the projected perimeter of a spudcan was drilled in this study. Th e relevant working conditions were shown in Table 5.…”

Section: Perforation Drillingmentioning

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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Section: Perforation Drillingmentioning

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

View full text Add to dashboard Cite

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Numerical investigation on reinstallation of jack-up unit with rectangular spudcan close to footprint

Yuan

Fan

et al. 2022

Ocean Engineering

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Numerical Investigation on the Spudcan Penetration into Sand Overlying Clay Considering the Strain Effects

et al. 2022

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A numerical model with a Coupled Eulerian–Lagrangian (CEL) approach is proposed for spudcan penetration into sand overlying clay. Both stress-dependence and strain-softening effects are incorporated into the M–C model to describe the sand, whereas the Tresca model with softening effect is used to describe the clay. Effects of the critical state strain threshold in the strain-softening model of sand and the clay sensitivity in the strain-softening model for clay are investigated. The model is verified against different soil conditions: uniform sand, loose sand overlying clay, and dense sand overlying clay. It is found that the stress-dependence effect dominates shallow penetration, whereas the strain-softening effect dominates deep penetration. The assumption of a constant peak friction angle for the accumulated deviatoric plastic strain less than the threshold of peak friction angle leads to an overestimation of the resistance in loose sand. Furthermore, the fit parameter obtained from triaxial tests tends to underestimate the peak resistance in dense sand. The proposed model should provide a valuable tool for geotechnical engineering analysis in sand.

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

Cited by 3 publications

References 18 publications

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

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

Numerical investigation on reinstallation of jack-up unit with rectangular spudcan close to footprint

Numerical Investigation on the Spudcan Penetration into Sand Overlying Clay Considering the Strain Effects

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