Experimental investigation of reverse end bearing of offshore shallow foundations

Mana, Divya S. K.; Gourvenec, Susan; Randolph, Mark

doi:10.1139/cgj-2012-0428

Cited by 61 publications

(18 citation statements)

References 27 publications

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“…The reduced peak uplift resistance observed may result partly from overloading during the jacked installation, leading to some remoulding of the soil -a characteristic that has been observed in previous tests (Mana et al, 2012c). The reduced peak uplift resistance may also be partly due to vibration of the tool table leading to minor cyclic loading of the foundation and a weaker reverse end bearing failure mechanism.…”

Section: Undrained Capacity In Compression and Uplift With Intact Skisupporting

confidence: 52%

“…Each of these issues have been addressed by previous research projects, results of which have provided increased confidence in relying on reverse end bearing for transient and limited sustained uplift (e.g. Gourvenec et al, 2009;Mana et al, 2012a) but caution over the effect of gapping -which can jeopardise the sustainability of reverse end bearing (Acosta-Martinez et al, 2010;Mana et al, 2012c). Experimental studies comparing the uplift response of skirted foundations with an intact and gapped skirtsoil interface have shown that, while full reverse end bearing can be mobilised with a sealed foundation with an intact skirt-soil interface, undrained uplift capacity is severely affected by loss of suction at small foundation displacements in the case of a gapped interface (Acosta-Martinez et al, 2010;Mana et al, 2012b).…”

Section: Introductionmentioning

confidence: 99%

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A novel technique to mitigate the effect of gapping on the uplift capacity of offshore shallow foundations

Mana¹,

Gourvenec

Randolph

2013

Géotechnique

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A flexible mat was provided around the periphery of skirted shallow foundations, a so-called 'gap arrestor', to assess the potential to mitigate the effect of gapping on uplift capacity. Results are presented from a series of drum centrifuge tests on skirted foundations with an intact skirt-soil interface, a gapped skirt-soil interface and a gapped interface with gap arrestor, subjected to undrained and sustained uplift. The results are promising, showing that the provision of an effective gap arrestor preserves suction to larger foundation displacements and reduces the rate of displacement under sustained uplift compared with the case of a gapped interface without arrestor.

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Section: Undrained Capacity In Compression and Uplift With Intact Skisupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

A novel technique to mitigate the effect of gapping on the uplift capacity of offshore shallow foundations

Mana¹,

Gourvenec

Randolph

2013

Géotechnique

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“…However, the reliability of under-base suction is conditional. Perforations of foundation base plates [10,11], loss of sealing through a drainage or vent valve, or a vertical gap along a skirt-soil interface for skirted shallow foundations [12] can provide access to free water and lead to dissipation of suction at the underside of the foundation. Sparse literature is available for shallow foundations under general loading with an interface unable to sustain tension, often referred to as a 'zero-tension' interface.…”

mentioning

confidence: 99%

Undrained capacity of surface foundations with zero-tension interface under planar V-H-M loading

Shen

Feng

Gourvenec

2016

Computers and Geotechnics

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Undrained capacity of strip and circular surface foundations with a zero-tension interface on a deposit with varying degrees of strength heterogeneity is investigated by finite element analyses. The method for simulating the zero-tension interface numerically is validated.Failure envelopes for strip and circular surface foundations under undrained planar V-H-M loading are presented and compared with predictions from traditional bearing capacity theory.Similar capacity is predicted with both methods in V-H and V-M loading space while the traditional bearing capacity approach under-estimates the V-H-M capacity derived from the numerical analyses due to superposition of solutions for load inclination and eccentricity not adequately capturing the true soil response. An approximating expression is proposed to describe the shape of normalised V-H-M failure envelopes for strip and circular foundations with a zero-tension interface. The unifying expression enables implementation in an automated calculation tool resulting in essentially instantaneous generation of combined loading failure envelopes and optimization of a foundation design as a function of foundation size or material factor. In contrast, the traditional bearing capacity theory approach or direct numerical analyses for a given scenario requires a raft of ad-hoc analyses covering a range of input variables in order to obtain the 'best' design.

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“…The undrained response in the HV plane and MV plane is symmetric around all axes, assuming full reversed end bearing for tension loads (Mana et al, 2013). Hence, one quadrant gives a full description of the full 360°failure envelope.…”

Section: Load Axis Symmetry Of the Failure Envelopesmentioning

confidence: 99%

A numerical study of capacity and stiffness of circular skirted foundations in clay subjected to combined static and cyclic general loading

2018

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Skirted foundations have been widely applied as offshore foundations for several decades. In design, the use of failure envelopes is convenient for assessing stability under combined loading. A large number of studies on failure envelopes exist in the literature based on experiments and numerical analyses. Most of these studies focus on ultimate capacity and static loading. This paper presents a numerical study focusing on cyclic degradation and failure envelopes for skirted foundations subjected to combined cyclic and static loading. It was found that the shapes of the failure envelopes are little affected by degradation expressed by the number of equivalent cycles. In addition to failure envelopes, contours of displacements were computed in the three-dimensional load space (vertical, horizontal and moment load) for a more complete description of the response. As an example, the well-defined cyclic contour diagrams of Drammen clay were utilised to demonstrate how foundation response diagrams can be established. The database is accompanied by a simplified procedure to account for cyclic degradation through equivalent number of cycles, different normalised load-displacement response and variation in foundation geometry. The framework of procedures can be used to estimate foundation stiffness and capacity and the results can serve as a basis for the development of foundation macro-element models.

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Experimental investigation of reverse end bearing of offshore shallow foundations

Cited by 61 publications

References 27 publications

A novel technique to mitigate the effect of gapping on the uplift capacity of offshore shallow foundations

A novel technique to mitigate the effect of gapping on the uplift capacity of offshore shallow foundations

Undrained capacity of surface foundations with zero-tension interface under planar V-H-M loading

A numerical study of capacity and stiffness of circular skirted foundations in clay subjected to combined static and cyclic general loading

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