Effect of strain rate and strain softening on embedment depth of a torpedo anchor in clay

Kim, Y. H.; Hossain, Muhammad Shazzad; Wang, Dong

doi:10.1016/j.oceaneng.2015.07.067

Cited by 78 publications

(12 citation statements)

References 34 publications

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“…The details of failure mechanisms associated with dynamic installation of different torpedo anchor configurations have been documented by Kim & Hossain (2015) and Kim et al (2015aKim et al ( , 2015b. Results in the following sections will focus on the pull-out behaviour of torpedo anchors, starting with a validation exercise against field test data.…”

Section: Resultsmentioning

confidence: 99%

“…The LDFE analyses were carried out using the coupled Eulerian-Lagrangian approach in the commercial FE package Abacus/Explicit (DS, 2012). Kim et al (2015aKim et al ( , 2015b provided an extensive information with regard to 3D dynamic installation and hence are not repeated here. The pull-out of the anchor at various angles at the padeye (θ a ), accounting for the soil conditions disturbed by the installation phase, was carried out applying an inclined displacement, rather than an inclined force, to obtain ultimate capacity.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study on pull-out capacity of torpedo anchors in clay

Kim

Hossain

2016

Géotechnique Letters

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This paper reports the results from dynamic finite-element analyses undertaken to provide insight into the behaviour of torpedo anchors during pullout in non-homogeneous clay. The results were validated against field data prior to undertaking a parametric study, exploring the relevant range of parameters in terms of installation effect, impact velocity, anchor geometry, padeye position, pullout angle. Installation method (e.g. quasi-static and dynamic installation) has shown significant influence on the vertical pullout capacity, but that influence reduced to marginal for lateral pullout. The inclined pullout capacity was dictated by the anchor weight and fully mobilised anchor-soil contact surface area and consequently the capacity increased with increasing the number of fins. Due to the lower weight and total surface area, the 45° (at the padeye) pullout capacity of the finless anchor was 29% of that of the considered four-fin anchor. The results showed that this percentage can be increased to 83% by shifting the padeye location of the finless anchor to 0·56 times the anchor shaft length from the top. Anchor capacity under inclined pullout loading was presented as failure envelopes expressed in terms of dimensionless vertical and horizontal components, which lied between the envelops developed for piles and embedded foundations.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical study on pull-out capacity of torpedo anchors in clay

Kim

Hossain

2016

Géotechnique Letters

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“…Parameters in terms of rate dependency and strain-softening were taken as η¼1.0; β¼0.1; ref γ ¼ 0.1 s À 1 ; δ rem ¼ 1/3; and ξ 95 ¼20, as they typically provided excellent match with the field and centrifuge tests data. More details of the influence of these parameters have also been investigated and reported in Kim et al (2015). Table 2) in soft clay with s u,ref ¼5 þ 2z kPa (note, the instantaneous velocity vector plots are not the same as for the real Lagrangian material, but the representation of the deformed soil flow in Eulerian element; e.g.…”

Section: Results and Discussion: Parametric Studymentioning

confidence: 99%

“…Adopt appropriate values for the bearing capacity factors N c,bA and N c,bF accounting for the geometry and the softening or (Low et al, 2010) and 7.5 (Skempton, 1951) can be considered for N c,bA and N c,bF , respectively due to the geometrical similarity noting that the effect of softening is small for torpedo anchor installation (Kim et al, 2015 (Einav and Randolph, 2006;Steiner et al, 2014;Chow et al, 2014).…”

Section: Bearing Resistance Methodsmentioning

confidence: 99%

Numerical investigation of dynamic installation of torpedo anchors in clay

Kim¹,

Hossain²,

Wang³

et al. 2015

Ocean Engineering

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a b s t r a c tThis paper reports the results from three-dimensional dynamic finite element analysis undertaken to provide insight into the behaviour of torpedo anchors during dynamic installation in non-homogeneous clay. The large deformation finite element (LDFE) analyses were carried out using the coupled EulerianLagrangian approach, modifying the simple elastic-perfectly plastic Tresca soil model to allow strain softening, and incorporate strain-rate dependency of the shear strength using the Herschel-Bulkley model. The results were validated against field data and centrifuge test data prior to undertaking a detailed parametric study, exploring the relevant range of parameters in terms of anchor shaft length and diameter; number, width and length of fins; impact velocity and soil strength. The anchor velocity profile during penetration in clay showed that the dynamic installation process consisted of two stages: (a) in Stage 1, the soil resistance was less than the submerged weight of the anchor and hence the anchor accelerated; (b) in Stage 2, at greater penetration, frictional and end bearing resistance dominated and the anchor decelerated. The corresponding soil failure patterns revealed two interesting aspects including (a) mobilization of an end bearing mechanism at the base of the anchor shaft and fins and (b) formation of a cavity above the shaft of the installing anchor and subsequent soil backflow into the cavity depending on the soil undrained shear strength. To predict the embedment depth in the field, an improved rational analytical embedment model, based on strain rate dependent shearing resistance and fluid mechanics drag resistance, was proposed, with the LDFE data used to calibrate the model.

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“…Recently, a Coupled Eulerian-Lagrangian (CEL) technique has been developed to overcome the limitations of the small deformation analyses. This technique has been applied to various geotechnical fields, such as the penetration of offshore structure [5][6][7][8][9], the landslide and debris flow [10,11], the pile penetration [12][13][14][15][16], and the effect on the nearby soil due to tunneling [17].…”

Section: Introductionmentioning

confidence: 99%

Application of a Coupled Eulerian-Lagrangian Technique on Constructability Problems of Site on Very Soft Soil

Jeong

Kim

2017

Applied Sciences

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This paper presents the application of the Coupled Eulerian-Lagrangian (CEL) technique on the constructability problems of site on very soft soil. The main objective of this study was to investigate the constructability and application of two ground improvement methods, such as the forced replacement method and the deep mixing method. The comparison between the results of CEL analyses and field investigations was performed to verify the CEL modelling. The behavior of very soft soil and constructability with methods can be appropriately investigated using the CEL technique, which would be useful tools for comprehensive reviews in preliminary design.

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Effect of strain rate and strain softening on embedment depth of a torpedo anchor in clay

Cited by 78 publications

References 34 publications

Numerical study on pull-out capacity of torpedo anchors in clay

Numerical study on pull-out capacity of torpedo anchors in clay

Numerical investigation of dynamic installation of torpedo anchors in clay

Application of a Coupled Eulerian-Lagrangian Technique on Constructability Problems of Site on Very Soft Soil

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