Use of a bounding surface model in predicting element tests and capacity in boundary value problems

Abstract

<jats:p> The paper examines the merit of a two surface plasticity model through an optimised calibration procedure and assesses the model performance in capturing the response at both element and system level. The governing equations are based essentially on the parent two surface plasticity model developed by Dafalias and Manzari (2004) with some simple yet practical changes to enable realistic predictions for monotonic loading along different load paths. This is achieved by scaling the influence of state parameter based on a normalised measure of anisotropy, thus leading to suitable change in dilatancy and plastic modulus for different loading directions. The paper presents a simple optimisation technique for calibrating the model parameters, providing an objective approach to reduce the uncertainties in parameter determination that leads to good agreement with responses measured in drained and undrained triaxial tests. The model has also been implemented for the boundary value problem of a buried circular plate anchor and a surface circular footing. Comparisons of the simulated responses with those measured in centrifuge tests demonstrate the potential of the model, whilst also pointing to the challenges in capturing the global response at all strain levels, even for rather simple boundary value problems. </jats:p>

An anchoring system for supporting platforms for wind energy devices

“…Proceedings of the Institution of Civil Engineers -Geotechnical Engineering, https://doi.org/10.1680/jgeen.22.00245 clay varied with anchor shape, soil strength and the depth below the seabed, normalised by anchor width (Aubeny, 2019;Das and Seeley, 1975;Giampa et al, 2019;Jalilvand et al, 2022;Lai et al, 2020;Liu et al, 2010Liu et al, , 2012Meyerhof and Adams, 1968;Neubecker and Randolph, 1996;O'Neill et al, 2003;Roy et al, 2021aRoy et al, , 2021bSahoo and Ganesh, 2018;Thorne, 1998;Vesic, 1971: Yu et al, 2015: Zhuang et al, 2022. Novel concepts such as the suction embedded plate anchor (Zook and Keith, 2009), OMNI-Max anchor (Kim and Hossain, 2017), multiline ring anchor (Lee et al, 2021, Lee andAubeny, 2020), fish anchor (Chang et al, 2019, Hossain et al, 2023 and dynamically embedded plate anchor (O'Loughlin et al, 2014) have been developed in recent years.…”

“…Therefore, carrying out investigations under 1g conditions may not be fully representative of the in situ conditions. On that note, there have been notable investigations carried out on plate anchors under elevated acceleration (centrifuge modelling by Giampa et al (2017) and Roy et al (2021aRoy et al ( , 2021b).…”

Towards a simple and reliable method for calculating uplift capacity of plate anchors in sand

“…( 20)). The implementation adopted here is detailed in Roy et al (2020) and summarised in Table 1 for completeness. Model parameters for the UWA silica sand (with index properties listed in Table 2) used in the centrifuge experiments were calibrated using an optimisation technique on triaxial compression and extension responses (Fig.…”

“…The FE analyses utilised a sophisticated bounding surface plasticity model that takes into account the variation of dilation with relative density, mean stress, direction of loading and progressive failure (elaborated in , Dafalias and Manzari 2004, Papadimitriou et al 2005 with some modifications that allow for fabric anisotropy. As described in Roy et al(2020), these simple and practical modifications avoid the more complex variations to the model described in Li and Dafalias (2012) and Petalas et al (2019), which would be required to account for cyclic loading reversals and stress rotations over multiple cycles, but are unnecessary for the monotonic loading conditions considered in this paper. Results from the FE analyses are validated against centrifuge model tests in loose and dense sand that consider plate anchors of different geometries, and at different embedment depths and gravitational acceleration levels.…”