Effect of soil deformability on the failure mechanism of shallow plate or screw anchors in sand

Cerfontaine, Benjamin; Knappett, Jonathan; Brown, Michael; Bradshaw, Aaron S.

doi:10.1016/j.compgeo.2019.01.007

Cited by 34 publications

(24 citation statements)

References 48 publications

(81 reference statements)

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“…This approach can be defined as a hybrid FE-Limit Analysis and has several advantages for prac cal design. It incorporates the effect of soil volumetric compression on the failure mechanism, unlike Limit Analysis (as reported in Cerfontaine et al 2019). In addi on, the approach does not require complex numerical solu ons to avoid problems resul ng from the use of strain-so ening models (Anastasopoulos et al 2007).…”

Section: Modelling Methodologymentioning

confidence: 99%

A finite element approach for determining the full load–displacement relationship of axially loaded shallow screw anchors, incorporating installation effects

et al. 2021

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Screw anchors have been recognised as an innovative solution to support offshore jacket structures and floating systems, due to their low noise installation and potential enhanced uplift capacity. Results published in the literature have shown that for both fixed and floating applications, the tension capacity is critical for design but may be poorly predicted by current empirical design approaches. These methods also do not capture the load-displacement behaviour, which is critical for quantifying performance under working loads. In this paper, a Finite Element methodology has been developed to predict the full tensile load-displacement response of screw anchors installed in sand for practical use, incorporating the effects of a pitch-matched installation. The methodology is based on a two-step process. An initial simulation, based on wished-in-place conditions, enables the identification of the failure mechanism as well as the shear strain distribution at failure. A second simulation refines the anchor capacity using soil-soil interface finite elements along the failure surface previously identified and also models installation through successive loading/unloading of the screw anchor at different embedment depths. The methodology is validated against previously published centrifuge test results. A simplified numerical approach has been derived to approximate the results in a single step.

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Section: Modelling Methodologymentioning

confidence: 99%

A finite element approach for determining the full load–displacement relationship of axially loaded shallow screw anchors, incorporating installation effects

et al. 2021

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“…The semi-analytical design approaches are mostly based on limit analysis, whose formulations are reviewed and summarised in [10]. These approaches usually depend on two main hypotheses: the definition of a failure mechanism and the stress distribution along it at the ultimate limit state (plastic collapse mechanism).…”

Section: (Semi-) Analytical Approachesmentioning

confidence: 99%

“…5-node interface elements are added between plate and soil elements to allow gap opening (no tension condition) and sliding. Boundary conditions are set far enough from the anchor to avoid boundary effects (7D below the anchor, 17D laterally [10]). The soil was assumed fully saturated, but the loading was deemed slow enough to ensure fully drained conditions.…”

Section: Definition Of the Fe Modelmentioning

confidence: 99%

“…The soil was assumed fully saturated, but the loading was deemed slow enough to ensure fully drained conditions. The mesh was chosen to be a good compromise between results accuracy and CPU time [10].…”

Section: Definition Of the Fe Modelmentioning

confidence: 99%

“…A detailed description of the parameters is given in [10] while a summary of the most important features is given in Table 1.…”

Section: Definition Of the Fe Modelmentioning

confidence: 99%

See 2 more Smart Citations

Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation

et al. 2019

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Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.

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Developing Screw Piles for Offshore Renewable Energy Application

Brown

Davidson

Cerfontaine

et al. 2020

Advances in Offshore Geotechnics

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This paper details the work undertaken at the University of Dundee in the last 5 years to develop understanding of screw piles to allow them to be deployed offshore as an alternative foundation type to driven piles used in jacket structures. This has been prompted by several UK and European funded research initiatives to develop silent foundation techniques to mitigate affects on marine mammals and other animals. Current mitigation systems also have significant associated costs and questionable environmental credentials. Prior to starting this work, it was recognized that development would not progress unless the ability to predict installation requirements did not form an early part of the research investigation. This then led to investigation of methods to reduce installation requirements and development of new design approaches for the required new screw pile geometries. This paper details the progress of these investigations which are still ongoing.

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Effect of soil deformability on the failure mechanism of shallow plate or screw anchors in sand

Cited by 34 publications

References 48 publications

A finite element approach for determining the full load–displacement relationship of axially loaded shallow screw anchors, incorporating installation effects

A finite element approach for determining the full load–displacement relationship of axially loaded shallow screw anchors, incorporating installation effects

Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation

Developing Screw Piles for Offshore Renewable Energy Application

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