Jack-up push-over analyses featuring a new force resultant model for spudcans in soft clay

Bienen, Britta; Cassidy, Mark

doi:10.1016/j.oceaneng.2014.02.008

Cited by 16 publications

(8 citation statements)

References 37 publications

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“…For longer skirt length ratio d/D  0.5, the effect of vertical loading is more prominent for all values of v.It can be seen that a larger h-m* failure envelope can be obtained for higher vertical mobilisation. The similar findings have been reported for spudcan foundations(Zhang et al, 2011(Zhang et al, , 2014. The data for various combinations of d/D and Ts/D (as tabulated inTable 3), normalised by the corresponding value for v = 0 (hv = 0 or m*v = 0), are plotted inFigure 17showing a reasonably unique trend of decreasing h/hv = 0 or m*/m*v = 0 with increasing v, which can be approximated as…”

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confidence: 75%

Capacity of skirted foundations in sand-over-clay under combined V-H-M loading

Zou

Hossain

et al. 2018

Ocean Engineering

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Circular skirted foundations are used widely in the offshore oil and gas industry and renewable energy industry to support subsea infrastructure and founding turbines. The foundations are subjected to combined vertical-horizontal-moment (V-H-M) loadings during operation. This paper describes an extensive investigation of the response of installed circular skirted foundations under operational loadings in sand-over-clay. The overarching aim was to examine the influence of the presence of a sand layer on the combined load capacity. A detailed parametric study was undertaken through small strain finite element analyses, varying the thickness of the sand layer, embedment depth of the foundation (or skirt length), and level of vertical load mobilization. The effect of the surface sand layer was profound for thicker sand layer of Ts/D> 0.2. Normalized failure envelopes were presented in v-h, v-m and h-m spaces. The FE results on the former two spaces showed unique trend, but not on the latter. New approximating expressions for describing the failure envelopes as a function of the sand layer thickness ratio, skirt length ratio and vertical load mobilization level were proposed.

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confidence: 75%

Capacity of skirted foundations in sand-over-clay under combined V-H-M loading

Zou

Hossain

et al. 2018

Ocean Engineering

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“…The limited space in the existing linear actuator unit precluded the use of a pair of actuators to generate the angular movement (such as used in the design of three-degrees-of-freedom VHM actuators for beam centrifuge by Dean et al (1997) and Punrattansin et al (2003) and more recently in the UWA drum by Zhang et al (2013Zhang et al ( , 2014aZhang et al ( , 2014bZhang et al ( , 2014c). Therefore, an innovative pulley system was developed for use in this study.…”

Section: Jack-up Modelmentioning

confidence: 99%

Development of a real-time hybrid testing method in a centrifuge

Kong¹,

Cassidy

Gaudin

2015

International Journal of Physical Modelling in Geotechnics

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This paper presents a pioneering real-time hybrid testing method for geotechnical centrifuges. The method was used to investigate the behaviour of a jack-up leg reinstalled near an existing footprint, a problem that is highly nonlinear, stress dependent and involves complex soil-structure interactions. By physically modelling only the footprintleg interaction and numerically modelling the rest of the jack-up structure, the method enables a realistic account of all the parameters involved in the interaction, including the footprint geometry, soil heterogeneity and structural properties of the jack-up unit. The paper also details the three-degree-of-freedom actuators developed to model the interaction, which features controlled loads and motions along the vertical, horizontal and moment directions, and the real-time algorithm that bridges the physical and numerical models. The algorithm allows the stiffness on each axis to be varied. Testing performed at 1g and in the centrifuge, modelling jack-ups with different stiffness on the horizontal and moment axes, is presented to validate the apparatus and methodology. The hybrid apparatus and real-time testing method were found to produce much more realistic boundary constraints than previous fixedsystem apparatuses, and this allowed the test results to be considerably more informative, accurate and useful.

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“…Historically, the assessment of spudcan fixity gave the first input to the development of macroelement plasticity models (Schotman, 1989;Schotman and Efthymiou, 1989). Years later, other authors went deeper into modelling soil-spudcan interaction in both sand and clay (Martin and Houlsby, 2001;Houlsby and Cassidy, 2002;Zhang et al, 2014b), and started to incorporate macroelements into jack-up structural analyses (Dean et al, 1997b;Cassidy et al, 2001Cassidy et al, , 2002Cassidy et al, , 2004Vlahos et al, 2008;Cassidy et al, 2010;Vlahos et al, 2011;Zhang et al, 2014a). A remarkable step forward was the extension to fully six-dimensional formulations Salciarini and Tamagnini, 2009;Tamagnini et al, 2013), that in turn enabled to analyse jack-ups under environmental loads of arbitrary orientation in the 3D space Cassidy, 2006, 2009).…”

Section: Modelling Of Spudcan Fixity In Jack-up Structural Analysesmentioning

confidence: 99%

Input of fully 3D FE soil-structure modelling to the operational analysis of jack-up structures

Pisanò

Schipper²,

Schreppers³

2019

Marine Structures

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Jack-ups are mobile structures widely employed in the offshore industry as drilling rigs or installation/maintenance vessels (e.g. for offshore wind farms). To assure safety at each location, site-specific assessment is required to predict the performance of the unit during installation and operations. The response of jack-ups to environmental loads is highly affected by the interaction between all footings (spudcans) and the underlying soil, an interaction still challenging to describe under general 3D loading. This work emphasises the potential of 3D continuum simulations to capture non-linear soilstructural interaction in jack-up units. An integrated jack-up-spudcans-soil 3D finite element (FE) model is set up by including strain-hardening soil plasticity and geometrical non-linearity (P − ∆ effects). After preliminary calibration of soil parameters, the FE model is successfully validated against literature results, namely obtained through (i) small-scale centrifuge experiments and (ii) numerical simulations based on macroelement foundation modelling. The validated FE model is then used to inspect several implications of soil modelling assumptions, as well as the response of the jack-up to relevant 3D loading combinations. The results presented support 3D continuum modelling as a suitable approach to analyse spudcan fixity and, overall, the operational performance of jack-ups. Despite higher conceptual/computational difficulties, fully 3D simulations can valuably complement the insight from (rare) integrated physical modelling, and contribute to the improvement of soil-spudcan macroelement models.

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Jack-up push-over analyses featuring a new force resultant model for spudcans in soft clay

Cited by 16 publications

References 37 publications

Capacity of skirted foundations in sand-over-clay under combined V-H-M loading

Capacity of skirted foundations in sand-over-clay under combined V-H-M loading

Development of a real-time hybrid testing method in a centrifuge

Input of fully 3D FE soil-structure modelling to the operational analysis of jack-up structures

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