A methodology to calibrate the PICSI cyclic p-y model using experimental results and optimisation

M. Guevara; J. P. Doherty; P. G. Watson; D. J. White

doi:10.1016/j.oceaneng.2023.115786

A methodology to calibrate the PICSI cyclic p-y model using experimental results and optimisation

M. Guevara, J. P. Doherty, P. G. Watson, D. J. White

Research output: Contribution to journal › Article › peer-review

Abstract

Fatigue life estimation of the components of a drilling conductor system is often a critical design consideration. The analysis is usually performed using a coupled system, with the soil-conductor interaction modelled using p-y springs that remain constant throughout the analysis. This means that shifts in bending moment profile that occur due to degradation and recovery of the soil during or after cycling are not accurately modelled. While the PICSI framework (White et al., 2022) can model changes in stiffness and strength of p-y curves due to cycling and pore-pressure dissipation, guidance has not yet been provided on how to calibrate its parameters. This paper presents an experimental methodology for this calibration process based on centrifuge and p-y model testing in reconstituted carbonate silt and kaolin clay. The procedure uses numerical optimisation, and the calibrated parameters are validated against results from an independent set of centrifuge tests on carbonate silt using a flexible pile of similar dimensions to a conductor. It is found that the calibrated model is able to match the changes in cyclic bending moment through a sequence of different packets of cyclic loading. This calibration procedure provides an objective approach for more accurate modelling of conductor fatigue.

Original language	English
Article number	115786
Journal	Ocean Engineering
Volume	287
DOIs	https://doi.org/10.1016/j.oceaneng.2023.115786
Publication status	Published - 1 Nov 2023

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title = "A methodology to calibrate the PICSI cyclic p-y model using experimental results and optimisation",

abstract = "Fatigue life estimation of the components of a drilling conductor system is often a critical design consideration. The analysis is usually performed using a coupled system, with the soil-conductor interaction modelled using p-y springs that remain constant throughout the analysis. This means that shifts in bending moment profile that occur due to degradation and recovery of the soil during or after cycling are not accurately modelled. While the PICSI framework (White et al., 2022) can model changes in stiffness and strength of p-y curves due to cycling and pore-pressure dissipation, guidance has not yet been provided on how to calibrate its parameters. This paper presents an experimental methodology for this calibration process based on centrifuge and p-y model testing in reconstituted carbonate silt and kaolin clay. The procedure uses numerical optimisation, and the calibrated parameters are validated against results from an independent set of centrifuge tests on carbonate silt using a flexible pile of similar dimensions to a conductor. It is found that the calibrated model is able to match the changes in cyclic bending moment through a sequence of different packets of cyclic loading. This calibration procedure provides an objective approach for more accurate modelling of conductor fatigue.",

keywords = "Conductors, Fatigue analysis, p-y curves, Soft soils, Subsea drilling systems, Whole life model",

author = "M. Guevara and Doherty, {J. P.} and Watson, {P. G.} and White, {D. J.}",

note = "Funding Information: The authors acknowledge the funding and execution of laboratory tests from the Norwegian Geotechnical Institute. The first author is supported by the ARC Industrial Transformation Research Hub for Offshore Floating Facilities which is funded by the Australian Research Council , Shell Australia , Woodside Energy , Bureau Veritas and Lloyd's Register ( IH140100012 ). The third author leads the Shell Chair in Offshore Engineering research team at The University of Western Australia, which is sponsored by Shell Australia . The fourth author acknowledges the support of the EPSRC Offshore Renewable Energy Supergen Hub (EPSRC grant ref. EP/S000747/1 ). Publisher Copyright: {\textcopyright} 2023 The Authors",

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AU - Doherty, J. P.

AU - Watson, P. G.

AU - White, D. J.

N1 - Funding Information: The authors acknowledge the funding and execution of laboratory tests from the Norwegian Geotechnical Institute. The first author is supported by the ARC Industrial Transformation Research Hub for Offshore Floating Facilities which is funded by the Australian Research Council , Shell Australia , Woodside Energy , Bureau Veritas and Lloyd's Register ( IH140100012 ). The third author leads the Shell Chair in Offshore Engineering research team at The University of Western Australia, which is sponsored by Shell Australia . The fourth author acknowledges the support of the EPSRC Offshore Renewable Energy Supergen Hub (EPSRC grant ref. EP/S000747/1 ). Publisher Copyright: © 2023 The Authors

PY - 2023/11/1

Y1 - 2023/11/1

N2 - Fatigue life estimation of the components of a drilling conductor system is often a critical design consideration. The analysis is usually performed using a coupled system, with the soil-conductor interaction modelled using p-y springs that remain constant throughout the analysis. This means that shifts in bending moment profile that occur due to degradation and recovery of the soil during or after cycling are not accurately modelled. While the PICSI framework (White et al., 2022) can model changes in stiffness and strength of p-y curves due to cycling and pore-pressure dissipation, guidance has not yet been provided on how to calibrate its parameters. This paper presents an experimental methodology for this calibration process based on centrifuge and p-y model testing in reconstituted carbonate silt and kaolin clay. The procedure uses numerical optimisation, and the calibrated parameters are validated against results from an independent set of centrifuge tests on carbonate silt using a flexible pile of similar dimensions to a conductor. It is found that the calibrated model is able to match the changes in cyclic bending moment through a sequence of different packets of cyclic loading. This calibration procedure provides an objective approach for more accurate modelling of conductor fatigue.

AB - Fatigue life estimation of the components of a drilling conductor system is often a critical design consideration. The analysis is usually performed using a coupled system, with the soil-conductor interaction modelled using p-y springs that remain constant throughout the analysis. This means that shifts in bending moment profile that occur due to degradation and recovery of the soil during or after cycling are not accurately modelled. While the PICSI framework (White et al., 2022) can model changes in stiffness and strength of p-y curves due to cycling and pore-pressure dissipation, guidance has not yet been provided on how to calibrate its parameters. This paper presents an experimental methodology for this calibration process based on centrifuge and p-y model testing in reconstituted carbonate silt and kaolin clay. The procedure uses numerical optimisation, and the calibrated parameters are validated against results from an independent set of centrifuge tests on carbonate silt using a flexible pile of similar dimensions to a conductor. It is found that the calibrated model is able to match the changes in cyclic bending moment through a sequence of different packets of cyclic loading. This calibration procedure provides an objective approach for more accurate modelling of conductor fatigue.

KW - Conductors

KW - Fatigue analysis

KW - p-y curves

KW - Soft soils

KW - Subsea drilling systems

KW - Whole life model

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VL - 287

JO - Ocean Engineering

JF - Ocean Engineering

M1 - 115786

ER -

A methodology to calibrate the PICSI cyclic p-y model using experimental results and optimisation

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