Undrained Load Capacity of Torpedo Anchors in Cohesive Soils

Aguiar, Cristiano S. de; Sousa, José Renato M. de; Ellwanger, Gilberto Bruno; Porto, Elisabeth de Campos; ́nior, Cipriano Jose ́ de M. Ju; Foppa, Diego

doi:10.1115/omae2009-79465

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…The pullout capacity of DPAs has been investigated experimentally through centrifuge model testing (O'Loughlin et al 2004;Richardson et al 2006Richardson et al , 2009. The holding capacity, for a given depth, increased with the number of fins due to the higher contact area (O'Loughlin et al 2004;de Aguiar et al 2009) and reduced as the pullout inclination rises from the horizontal (de Aguiar et al 2009). As is generally the case for suction caissons, once the load inclination exceeded about 30 to the horizontal, the capacity was governed entirely by the vertical capacity.…”

Section: Data From Centrifuge Testmentioning

confidence: 99%

Experimental Investigation of Installation and Pullout of Dynamically Penetrating Anchors in Clay and Silt

Hossain

Kim

Gaudin

2014

J. Geotech. Geoenviron. Eng.

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This paper reports the results from a series of model tests undertaken to provide insight into the behaviour of torpedo anchors during dynamic installation and pullout in lightly overconsolidated kaolin clay and calcareous silt. The tests were carried out in a drum centrifuge at 200 g, varying the drop height, hence the impact velocity, and the time delay for consolidation prior to pullout. The pullout angle at the mudline was also varied to encompass various mooring systems, including catenary (0), taut leg (45) and tension leg (~80). Two geometries of torpedo anchors were explored, varying fin and tip geometry. The results demonstrated that the anchor embedment depth increased as the drop height (and hence the impact velocity) increased and the soil undrained shear strength decreased. In stronger silt, the cavity above the installing anchor remained open whereas in soft clay, it was fully backfilled and replenished. The corresponding anchor embedment depth was also about 0.63 times compared to that in clay. The anchor holding capacity was found to increase with increasing post-installation consolidation time, depth of embedment and soil undrained shear strength and with reducing pullout angle at the mudline. The anchor rotation during pullout and hence the pullout distance for attaining the maximum capacity reduced as the load

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Section: Data From Centrifuge Testmentioning

confidence: 99%

Experimental Investigation of Installation and Pullout of Dynamically Penetrating Anchors in Clay and Silt

Hossain

Kim

Gaudin

2014

J. Geotech. Geoenviron. Eng.

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“…The pullout capacity of dynamically penetrating anchors has been investigated experimentally through centrifuge model testing (O'Loughlin et al, 2004;Richardson et al, 2006Richardson et al, , 2009) and numerically (de Aguiar et al, 2009;Sagrilo et al, 2010), with limited results from field trials also being available. Results indicate that simple bearing capacity calculations summing endbearing and shaft resistance are appropriate for the vertical component of the anchor holding capacity, provided that the embedment (and hence the local soil strength) is accurately predicted.…”

Section: Dynamically Penetrating Anchorsmentioning

confidence: 99%

“…Results indicate that simple bearing capacity calculations summing endbearing and shaft resistance are appropriate for the vertical component of the anchor holding capacity, provided that the embedment (and hence the local soil strength) is accurately predicted. The holding capacity, for a given embedment, increases with the number of flukes due to the higher contact area (O'Loughlin et al, 2004;de Aguiar et al, 2009) and reduces as the pullout inclination rises from the horizontal (de Aguiar et al, 2009). As for suction caissons, once the load inclination exceeds about 30 º to the horizontal, the capacity is governed entirely by the vertical capacity.…”

Section: Dynamically Penetrating Anchorsmentioning

confidence: 99%

Recent advances in offshore geotechnics for deep water oil and gas developments

et al. 2011

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The paper presents an overview of recent developments in geotechnical analysis and design associated with oil and gas developments in deep water. Typically the seabed in deep water comprises soft, lightly overconsolidated, fine grained sediments, which must support a variety of infrastructure placed on the seabed or anchored to it. A particular challenge is often the mobility of the infrastructure either during installation or during operation, and the consequent disturbance and healing of the seabed soil, leading to changes in seabed topography and strength. Novel aspects of geotechnical engineering for offshore facilities in these conditions are reviewed, including: new equipment and techniques to characterise the seabed; yield function approaches to evaluate the capacity of shallow skirted foundations; novel anchoring systems for moored floating facilities; pipeline and steel catenary riser interaction with the seabed; and submarine slides and their impact on infrastructure. Example results from sophisticated physical and numerical modelling are presented.

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“…Torpedo-shaped anchors are able to withstand permanent loads (Medeiros & et,2006) are reported that the torpedo-shaped anchor in January 2000 RasinCampos, Sea, Brazil, Petrobras over ninety torpedo without fins (finless) with dimensions of 12 m length, 0.76 m diameter and weighing 240 KN[3]. (Aguiar & 2009) are showed in another project torpedo-shaped anchor are used with the same length and diameter, but with a weight of 421 KN with tetrapterous (4 fins) The longitudinal fins connected along the cylinder. The anchors were installed with the free fall and aim to a FPSO in depth water, over 1,400 m. In the other 6 anchor torpedo-shaped device with a diameter of 1.07 m, 17 m long and 961 KN for each to control weight [4].…”

Section: Previous Researchmentioning

confidence: 99%

Comparison of Simulation of Torpedo-shaped Anchor whit and without fins for submersible offshore platforms under tensile force

2016

Scinzer j. eng.

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: Due to the increasing exploration projects, derivation and removal of hydrocarbon reservoirs in deep water and the impossibility or difficulty and cost of access to the sea bed, for holding a variety of immovable oil platforms, Offshore and marine structure engineering try to extend to using floating and semi-submersible platforms in deep-water in the world. Due to the deployment of these platforms, it is necessary to connect the anchor to the seabed with mooring line and keep the platforms stable and immovable. Torpedo-shaped anchors, with advantages such as cheap, easy to install, you can re-use and fast installation and do not require special tools to install the agents and contractors further consideration and they are interested in using torpedo anchors for semi-submersible and floating platforms. Few studies of the behavior of torpedo anchor on the sea bed's soil in laboratory and field have been done. In this research, torpedo anchor under tensile force is modeled under tensile force and it is drawn out from inside of soil. For this purpose, the method was used to determine is the specific torpedo location change in soil. Finite element modeling software is used to show soil and a torpedo-shaped behaviors. And finally capacities that they are obtained by calculating (the forces and capabilities) were compared using API Regulations. The diagram of displacement and force, force: time and displacement: time and without dimension diagram: displacements divides diagonal and force divides weight for modeling the Eulerian soil was drawn. The output results express that for finny torpedo-shaped anchors with obtained capacity is increased. The output results can be seen by examining the capacities obtained by modeling finite element software capacity and the calculation formulas are reasonably consistent API Regulations. According to software result torpedo-shaped, in same main cylinder shape, anchors with fins express considerable resistance capacity compare with torpedo shape anchors without fins under tensile force.

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Undrained Load Capacity of Torpedo Anchors in Cohesive Soils

Cited by 6 publications

References 2 publications

Experimental Investigation of Installation and Pullout of Dynamically Penetrating Anchors in Clay and Silt

Experimental Investigation of Installation and Pullout of Dynamically Penetrating Anchors in Clay and Silt

Recent advances in offshore geotechnics for deep water oil and gas developments

Comparison of Simulation of Torpedo-shaped Anchor whit and without fins for submersible offshore platforms under tensile force

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