Setup Characteristics of Suction Anchors for Soft Gulf of Mexico Clays:Experience From Field Installation and Retrieval

Jeanjean, Philippe

doi:10.4043/18005-ms

Cited by 18 publications

(7 citation statements)

References 4 publications

(13 reference statements)

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“…Following the approach adopted by Jeanjean (2006), Richardson et al (2009) and Hossain et al (2015), the relative increase in anchor capacity was determined through consideration of the net capacity FN relative to the immediate capacity FN,0 and the ultimate long term capacity FN,max, and assumed linked to the degree of consolidation by…”

Section: Effect Of Reconsolidation Time T C After Caisson Installationmentioning

confidence: 99%

Installation and Monotonic Pullout of a Suction Caisson Anchor in Calcareous Silt

Koh

Hossain

Kim

2017

J. Geotech. Geoenviron. Eng.

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This paper reports results from a series of model tests undertaken to provide insight into the behaviour of a stiffened caisson anchor during installation and monotonic pullout in lightly overconsolidated calcareous silt. The tests were carried out in a beam centrifuge, varying the installation process (jacked in or jacked in followed by suction assisted installation), and the consolidation period prior to anchor pullout. The mudline load inclination was also varied to encompass various mooring configurations. The centrifuge data were used to calibrate analytical installation and vertical pullout capacity models, based on conventional bearing and frictional resistance factors but with strain rate dependent and strain softened undrained shear strength for the soil. Piezocone based direct design approaches were also proposed, deriving end bearing and frictional resistance from cone tip resistance and sleeve friction, respectively. Holding capacity of suction caisson under inclined loading was presented as failure envelopes expressed in terms of dimensionless vertical and horizontal components of caisson net resistance, which agreed well with a plastic limit analysis based envelope developed for suction caissons in clay. The regain of anchor capacity was found to be in good agreement with predictions based on the cavity expansion framework.

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Section: Effect Of Reconsolidation Time T C After Caisson Installationmentioning

confidence: 99%

Installation and Monotonic Pullout of a Suction Caisson Anchor in Calcareous Silt

Koh

Hossain

Kim

2017

J. Geotech. Geoenviron. Eng.

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“…Following the approach adopted for torpedo anchors (Richardson et al, 2009) and suction caissons (Jeanjean, 2006), the relative increase in anchor capacity was determined through consideration of the net capacity F N relative to the immediate capacity F N,0 and the ultimate long-term capacity F N,max , and assumed linked to the degree of consolidation by Figure 14(b) shows the results for tests T11, T12 and T13, plotted against dimensionless time, T ¼ c h t c =D 2 A , indicating the progression of anchor capacity (due to reconsolidation) with time after installation. Equivalent centrifuge model test data for torpedo anchors in kaolin clay reported by Richardson et al (2009) are also included in Fig.…”

Section: Effect Of Reconsolidation Time T C After Anchor Installationmentioning

confidence: 99%

Dynamic installation and monotonic pullout of a torpedo anchor in calcareous silt

Hossain¹,

O’Loughlin²,

Kim³

2015

Géotechnique

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Challenges associated with dynamically installed anchors include prediction of the anchor embedment depth, which dictates the anchor's holding capacity. This is particularly true for calcareous sediments, as very little performance data exist for this anchor type in these soils. This paper reports results from a series of model tests undertaken to provide insight into the behaviour of a torpedo anchor during dynamic installation and monotonic pullout in lightly overconsolidated calcareous silt. The tests were carried out in a beam centrifuge, varying the drop height and consequently the impact velocity, and the consolidation period prior to anchor pullout. The mudline load inclination was also varied to encompass various mooring configurations. The centrifuge model test data were used to calibrate: (a) an analytical dynamic embedment model, based on conventional bearing and frictional resistance factors but with strain-rate-dependent undrained shear strength for the soil; and (b) an analytical quasi-static vertical pullout capacity model, accounting for reverse end bearing and frictional resistance. A total energy based expression, appropriate for calcareous silts, was proposed for predicting anchor embedment depth for a given anchor geometry, mass and impact velocity. For assessing anchor vertical holding capacity, a piezocone based direct design approach was also proposed, deriving anchor end bearing and frictional resistance from cone tip resistance and sleeve friction, respectively. Anchor capacity under inclined loading was presented as failure envelopes expressed in terms of dimensionless vertical and horizontal components of anchor net resistance, which agreed well with a finite-element based envelope developed for embedded foundations. The regain of anchor capacity was found to be in good agreement with predictions based on the cavity expansion framework.

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“…Some of the strength gain observed by Jeanjean (2006) in the GoM database shortly after the installation perhaps can be attributed to thixotropy. During that time, the pore pressures adjacent to the pile shaft are high, resulting in very low effective stresses.…”

Section: Implications For Gom Field Situations Thixotropymentioning

confidence: 99%

“…Jeanjean (2006) analysed resistances from installation and retrieval of suction anchors (shortly after installation) in the GoM. He concluded that thixotropy alone appears to provide a good lower bound estimate of ultimate axial capacity, but Fig.…”

Section: Implications For Gom Field Situations Thixotropymentioning

confidence: 99%

“…It should be noted that uncertainty still remains for estimating axial pile capacity after dissipation of excess pore pressures based on existing recommendations for calculation of aging effects (Fellenius, 2008). With respect to thixotropy, Jeanjean (2006) concluded that suction anchors will reach 90% consolidation after about 30 days in the GoM, when their axial capacity can be estimated using the conventional approaches described in standards (e.g. API RP2A-WSD, API, 2007); however, more data and investigation are needed to confirm the set-up characteristics between 1 and 30 days.…”

Section: Well Design and Jetting Operationmentioning

confidence: 99%

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Long-term axial capacity of deepwater jetted piles

Zakeri¹,

Liedtke²,

Clukey³

et al. 2014

Géotechnique

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Jetting is a technique commonly used to install well conductors, which is faster than the conventional drill and cement method. Conductors are designed to support the buoyed weight of the first string of casings (typically, 3-5 days after jetting) and later to provide the lateral stability for the well system against cyclic loading from environmental elements. The axial bearing capacity of a jetted conductor increases with time due to consolidation and thixotropy effects; however, the field data for set-up only extend to about 10 days. Installation of jetted conductors as piles and anchors may be an economic solution for offshore developments. The long-term axial capacity of jetted conductors was investigated through a series of centrifuge modelling and laboratory thixotropy testing. The centrifuge tests simulated jetting installation of four model conductors and measured capacities at set-up times ranging between 10 and 1000 days in a kaolin clay seabed with an undrained shear strength profile similar to that encountered in deepwater Gulf of Mexico. The centrifuge test results were compared to the field data in the Gulf of Mexico. The implications of the centrifuge test results for deepwater Gulf of Mexico conditions are discussed. A method is presented for estimating the long-term axial capacity of jetted conductors in Gulf of Mexico seabed conditions with recommendations for additional studies.

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Setup Characteristics of Suction Anchors for Soft Gulf of Mexico Clays:Experience From Field Installation and Retrieval

Cited by 18 publications

References 4 publications

Installation and Monotonic Pullout of a Suction Caisson Anchor in Calcareous Silt

Installation and Monotonic Pullout of a Suction Caisson Anchor in Calcareous Silt

Dynamic installation and monotonic pullout of a torpedo anchor in calcareous silt

Long-term axial capacity of deepwater jetted piles

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