Installation of Suction Anchors in Layered Soils

Saue, Morten; Aas, P; Andersen, KH; Solhjell, E.

doi:10.3723/osig17.507

Cited by 6 publications

(7 citation statements)

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“…Example 1 Saue et al (2017) presented the installation records for a suction anchor installed in a soil profile that is summarized in Table 2. The soil profile consists of two clay units (II and III) overlying a sand unit (IV).…”

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

“…The soil profile consists of two clay units (II and III) overlying a sand unit (IV). In Saue et al (2017), the given strength profile was used together with a best estimate sensitivity factor of 2.2 in the clay layers (Units II and III) and strength anisotropy ratios of s DSS u =s C u ¼ 0.8 and s AV u =s C u ¼ 0.6. In the sand layer, an earth pressure coefficient of K ¼ 0.8 was used together with a ratio between inside and outside permeabilities estimated to be k i =k o ¼ 5 and with an effective friction angle derived from the measured tip resistance (q c ) of the CPT and the database of sands presented in Andersen and Schjetne (2013).…”

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

“…An oedometer modulus of M ¼ 40,000 kPa together with an outside permeability of k o ¼ 10 −5 m=s was used for the plug lift analysis. The following parameters were not presented in Saue et al (2017) and, as a result, were estimated for this analysis: k i =k o , M, k o , and t.…”

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

“…Thus, only penetration resistance to a depth of 7 m prior to the onset of cycling is considered in the following. For more details see Saue et al (2017). Fig.…”

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

“…The potential for a large plug lift and for high tip resistance in the sand layer is the main reason to either avoid these locations, only penetrate into the clay, or modify anchors with flow channels to ensure the flow of water through the sand layers, as detailed in Aas et al (2009). However, several recent installations indicate that a seepage flow can be mobilized in a sand layer that is overlain by an impermeable layer (Houlsby and Byrne 2005b;Saue et al 2017;Panayides et al 2017). This has also been observed in centrifuge tests reported by Watson et al (2006), Tran et al (2007), and Senders et al (2007).…”

Section: Introductionmentioning

confidence: 99%

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Penetration Model for Installation of Skirted Foundations in Layered Soils

Klinkvort

Sturm

Andersen

2019

J. Geotech. Geoenviron. Eng.

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During installation of a skirted foundation, resistance to penetration is a combination of side and tip resistances. When penetrating a permeable soil unit, tip resistance in particular can be high but if seepage water flow from the outside to the inside of the skirted foundation exists, the pore water gradient will reduce the effective stresses and therefore also penetration resistance. Recent installation data from the field and laboratory suggest that this effect can also occur during installation in layered profiles. This paper presents a model that accounts for seepage flow in unlimited permeable layers that are overlain by one or several impermeable layers. The model assumes that seepage flow in the underlying sand layer is induced by an incremental lift of the internal soil plug, which enables the transfer of some of the differential pressure applied under the foundation lid to the bottom of the lifted soil plug. A single equation is proposed to calculate the critical suction number for layered soil conditions that can be used with an empirical model to calculate the reduction in penetration resistance. A calibration of the proposed equation for the critical suction number is carried out using an axis symmetrical finite-element model that uses a linear elastic soil model and assumes steady-state flow conditions. The calibration of the proposed equation for calculating the critical suction number was first carried out for a homogenous permeable soil. This was done to benchmark the model against previously published data. In a second step, the calibration was done for a layered profile and different flow boundary conditions. The proposed penetration model is demonstrated by back-calculating full-scale installations. The paper closes with a discussion of the main assumption of plug lift, and a simple model to evaluate the degree of plug lift is proposed.

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Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

“…Thus, only penetration resistance to a depth of 7 m prior to the onset of cycling is considered in the following. For more details see Saue et al (2017). Fig.…”

Section: Demonstration Of the Extended Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Penetration Model for Installation of Skirted Foundations in Layered Soils

Klinkvort

Sturm

Andersen

2019

J. Geotech. Geoenviron. Eng.

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Analytical solution for suction-induced seepage flow during suction bucket installation in multilayered soil with anisotropic permeability

Huang,

Shi,

Zhou

et al. 2024

Computers and Geotechnics

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Observations of the Effects of a Clay Layer on Suction Bucket Installation in Sand

Ragni

Bienen

O’Loughlin

et al. 2020

J. Geotech. Geoenviron. Eng.

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Suction buckets are becoming established as a viable foundation solution for offshore wind turbines. In sand, suction-induced seepage flow reduces effective stresses at the skirt tips, which decreases penetration resistance. However, layered seabeds are often encountered in areas of offshore wind farm development. The effect of the presence of a clay layer on the suction-induced seepage flow in the sand layer is not well understood. Therefore in this study, the effects of a clay layer on suction bucket installation in dense sand was investigated by analysing images of a half-bucket installed against a Perspex window captured during tests performed in a geotechnical centrifuge, such that the stress levels are realistic and relevant to field conditions. Installations in sand-over-clay were unproblematic and characterised by deformation of the sand-clay interface, with no clear interruption of the seepage flow.Installations in clay-over-sand were also successful. Uplift of the clay plug was identified as the mechanism to transfer suction to the underlying sand, creating seepage flow and thus facilitating further skirt penetration rather than terminating the installation.

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Installation of Suction Anchors in Layered Soils

Cited by 6 publications

References 0 publications

Penetration Model for Installation of Skirted Foundations in Layered Soils

Penetration Model for Installation of Skirted Foundations in Layered Soils

Analytical solution for suction-induced seepage flow during suction bucket installation in multilayered soil with anisotropic permeability

Observations of the Effects of a Clay Layer on Suction Bucket Installation in Sand

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