Penetration of dynamically installed anchors in clay

O’Loughlin, Conleth; Richardson, Mark D.; Randolph, Mark; Gaudin, Christophe

doi:10.1680/geot.11.p.137

Cited by 113 publications

(56 citation statements)

References 30 publications

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“…After ten cycles, the net penetration resistance is 0·4 times the initial resistance, indicating a sensitivity (in terms of penetration resistance) of 2·5 which is typical of that reported in previous studies on UWA kaolin (Chen and Randolph, 2008;O'Loughlin et al, 2013;Sahdi et al, 2014;Watson et al, 2000).…”

supporting

confidence: 77%

Experience with a dual pore pressure element piezoball

Colreavy

O’Loughlin

Randolph

2016

International Journal of Physical Modelling in Geotechnics

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Piezoballs, which are full-flow ball penetrometers incorporating pore pressure measurements, are an attractive soft soil characterisation tool as they allow measurement of the intact and remoulded strength and the consolidation coefficient in a single test. The merit of full-flow penetrometers as a reliable tool that is superior to the cone in quantifying the strength of soft clay is gaining acceptance. Much of the recent focus on piezoballs has been on the pore pressure measurement location. Prompted by recent studies that highlight the merit of measuring pore pressure concurrently at more than one measurement location, this paper considers a new centrifuge-scale piezoball, with simultaneous pore pressure measurement at the equator and mid-face positions. Results from centrifuge tests in normally consolidated kaolin clay form the basis for the examination and yield coefficients of consolidation that are consistent with values derived using a number of different methods. Although the mid-face position appears to be the more sensible pore pressure measurement position for dissipation tests, consideration of the values measured at both positions provide strong indications of the drainage response during penetration that is shown in the paper to be important for deriving coefficients of consolidation from subsequent dissipation phases.

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supporting

confidence: 77%

Experience with a dual pore pressure element piezoball

Colreavy

O’Loughlin

Randolph

2016

International Journal of Physical Modelling in Geotechnics

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“…As shown in Figs. 9 and 11, a low estimation of the decrement slope of the velocity in the soil and the final embedment depth in the analytical results guarantee a conservative estimation and time consumption if the CEL method-based numerical analysis works well and reports precise values, as in several previous studies O'Loughlin, , 2013Hossain, 2014). In Fig.…”

Section: Validation Of Analytical Analysissupporting

confidence: 54%

“…It is chiefly based on Newtonian mechanics and assumes uniform clay. Several investigations have used similar approaches based on True's model for freefall anchor installation (de Araujo, 2004;Brandão, 2006;O'Loughlin, , 2013Hossain, 2014). A modified equation of motion is shown in Eq.…”

Section: Modified Bearing Resistance Approachmentioning

confidence: 99%

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Damage Assessment of Free-fall Dropped Object on Sub-seabed in Offshore Operation

Won

Kim²,

Park

et al. 2015

Journal of Advanced Research in Ocean Engineering

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This paper presents the damage assessment of a free-fall dropped object on the seabed. The damage to a dropped object totally depends on the relationship between the impact energy and the soil strength at the mudline. In this study, unexpected dropping scenarios were first assumed by varying the relevant range of the impact velocity, structure geometry at the moment of impact, and soil strength profile along the penetration depth. Theoretical damage assessments were then undertaken for a free-fall dropping event with a fixed final embedment depth for the structure. This paper also describes the results of a three-dimensional large deformation finite element analysis undertaken for the purpose of validation. The analyses were carried out using the coupled Eulerian-Lagrangian approach, modifying the simple elastic-perfectly plastic Tresca soil model. The validation exercises for each dropping scenario showed good agreement, and the present numerical approach was capable of predicting the behavior of a free-fall dropped object.

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“…The cost of installing anchors increases exponentially as water depths increase, which has inspired the development of dynamically penetrating anchors that embed themselves into the seabed under free-fall and thus are less sensitive to increasing water depth compared to conventional concepts [112,113]. Dynamically penetrating anchors or termed as Gravity-installed anchors are usually released from a height of 50-100 m above the seabed and reach velocities of 20-30 m/s at the seabed, eventually installed to the tip penetration of 1.5-3 times their length.…”

Section: Dynamically Penetrating Anchorsmentioning

confidence: 99%

On the instability of offshore foundations: theory and mechanism

Gao

et al. 2015

Sci. China Phys. Mech. Astron.

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As the offshore engineering moving from shallow to deep waters, the foundation types for fixed and floating platforms have been gradually evolving to minimize engineering costs and structural risks in the harsh offshore environments. Particular focus of this paper is on the foundation instability and its failure mechanisms as well as the relevant theory advances for the prevailing foundation types in both shallow and deep water depths. Piles, spudcans, gravity bases, suction caissons, and plate anchors are detailed in this paper. The failure phenomena and mechanisms for each type of foundations are identified and summarized, respectively. The theoretical approaches along with sophisticated empirical solutions for the bearing capacity problems are then presented. The major challenges are from flow-structure-soil coupling processes, rigorous constitutive modeling of cyclic behaviors of marine sediments, and the spatial variability of soil properties for large-spreading structures. Further researches are suggested to reveal the instability mechanisms for underpinning the evolution of offshore foundations. Citation:Gao F P, Li J H, Qi W G, et al. On the instability of offshore foundations: theory and mechanism.

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Penetration of dynamically installed anchors in clay

Cited by 113 publications

References 30 publications

Experience with a dual pore pressure element piezoball

Experience with a dual pore pressure element piezoball

Damage Assessment of Free-fall Dropped Object on Sub-seabed in Offshore Operation

On the instability of offshore foundations: theory and mechanism

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