A systematic approach to offshore engineering for multiple-project developments in geohazardous areas

Evans, Trevor

doi:10.1201/b10132-6

Cited by 21 publications

(18 citation statements)

References 2 publications

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“…9 and ranges from about 3.7 at the mud line up to 1.3 at a depth of 10 m. As seen, the range of values of X Sn are in good agreement with [23]. This study considered pipelines buried in a range of soil cover depth (H) ranging from 1 to 3 m of depth.…”

Section: Probabilistic Considerations For the Parameters In The Analysessupporting

confidence: 79%

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Reliability functions for buried submarine pipelines in clay subjected to upheaval buckling

Valle-Molina

Alamilla

Sánchez-Moreno

et al. 2014

Applied Ocean Research

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Section: Probabilistic Considerations For the Parameters In The Analysessupporting

confidence: 79%

“…Typically, shear strength of fine soils reduces from 2 to 5 times when soil changes from an intact to a fully remolded state (White and Cathie [23]). …”

Section: Lower-bound Uplift Capacity In Fine Soilsmentioning

confidence: 99%

Reliability functions for buried submarine pipelines in clay subjected to upheaval buckling

Valle-Molina

Alamilla

Sánchez-Moreno

et al. 2014

Applied Ocean Research

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“…A small-scale direct shear box modified at The University of Western Australia (UWA) to operate at the low stress levels relevant to pipeline geotechnics was used by White and Cathie (2011) and White et al (2012) in measuring the partially drained interface shear strength at a normal stress of 2.5 kPa for a rough steel surface against kaolin clay and carbonate soils, respectively. In the UWA low-stress shear box, the lower half of the shear box is placed with a coated or uncoated plate.…”

Section: Introductionmentioning

confidence: 99%

Residual shear strength of fine-grained soils and soil–solid interfaces at low effective normal stresses

et al. 2015

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A laboratory research program was undertaken to study the large-strain shear strength characteristics of fine-grained soils under low effective normal stresses (ϳ3-7 kPa). Soils that cover a wide range of plasticity and composition were utilized in the program. The interface shear strength of these soils against a number of solid surfaces having different roughness was also investigated at similar low effective normal stress levels. The findings contribute to advancing the knowledge of the parameters needed for the design of pipelines placed on sea beds and the stability analysis of shallow soil slopes. A Bromhead-type torsional ring-shear apparatus was modified to suit measuring soil-soil and soil-solid interface residual shear strengths at the low effective normal stresses. In consideration of increasing the accuracy of assessment and depicting the full-scale field behavior, the interface residual shear strengths were also measured using a macroscale interface direct shear device with a plan interface shear area of ϳ3.0 m 2 . Correlations are developed to estimate the soil-soil and soil-solid interface residual shear strengths at low effective normal stresses. The correlations are compared with soil-soil and soil-solid interface drained residual shear strengths and correlations presented in the literature.

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“…Deterministic calculations use combinations of soil strength parameters, e.g., LE intact strength gradient with HE soil sensitivity, and vice versa, to determine the widest range in pipe embedment. Probabilistic calculations, using a Monte Carlo approach, allow the full variability in soil strength parameters (and by extension the variability in lay conditions) to be captured naturally, assuming the inputs are uncorrelated (or partially correlated, if desired) (White and Cathie 2011).…”

Section: Predictions Of As-laid Embedmentmentioning

confidence: 99%

“…For pipelines laid and operated on the seabed, the pipe embedment has a significant impact on lateral and axial seabed resistance (White and Cathie 2011). This in turn has a significant influence on the global behaviour of the pipeline during operation.…”

Section: Introductionmentioning

confidence: 99%

Modelling spatial variability in as-laid embedment for high pressure and high temperature (HPHT) pipeline design

2016

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Subsea pipelines are being designed to accommodate higher temperatures and pressures. Current modelling approaches that adopt constant lateral seabed resistance along the pipeline do not capture the high spatial variability in as-laid pipeline embedment from field observations, which strongly affects the lateral resistance. Ignoring spatial variability when designing pipelines with engineered buckles leads to higher predictions of axial force along the pipeline, with reduced likelihood of buckle formation. This can result in excessive mitigation measures being adopted, such as sleepers or counteract structures, which significantly increase project costs. Spatial variability of pipeline embedment is not currently handled rationally in design because an understanding of the physical mechanisms that cause as-laid embedment and methods for accurately predicting it have only recently emerged. This paper illustrates how the influence of these physical mechanisms that drive embedment can be extracted from field survey data and then modelled synthetically in design analyses. The impact of embedment variability and the resulting variation in lateral seabed resistance on the lateral buckling response is illustrated. The framework represents an improvement in the way geotechnical uncertainty and variability is handled in pipeline-seabed interaction analyses for use in pipeline design, and has already begun to be implemented in practice.Key words: pipeline embedment, pipeline design, high pressure and high temperature (HPHT), lateral buckling, modelling, spatial variability. Résumé :Les pipelines sous-marins sont conçus pour tenir compte des pressions et des températures plus élevées. Les approches de modélisation actuelles qui adoptent la résistance latérale constante aux fonds marins le long du pipeline ne tiennent pas compte de la forte variabilité spatiale d'enrobement de pipelines installés à partir des observations sur le terrain, qui influe fortement la résistance latérale. Ignorer la variabilité spatiale lors de la conception des pipelines avec des boucles conçues aboutit à des prévisions plus élevées de force axiale le long du pipeline, avec une probabilité réduite de formation de boucle. Cela peut entraîner de mesures adoptées d'atténuation excessive, telles que des sous-poutres ou des structures de compensation, ce qui augmente les coûts du projet. La variabilité spatiale d'un enrobage de pipeline n'est pas actuellement traitée rationnellement dans la conception, car la compréhension des mécanismes physiques qui causent des enrobages d'installation, et les méthodes pour prédire avec précision, ont émergé que récemment. Cet article illustre comment l'influence de ces mécanismes physiques qui produisent un enrobage peut être extraite des données d'enquêtes de terrain, et puis modelée synthétiquement dans des analyses de conception. L'impact de la variabilité d'enrobage et la variation résultante de la résistance latérale du fond marin à la réponse du flambement latéral sont illustrés. Le cadre de travail ...

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A systematic approach to offshore engineering for multiple-project developments in geohazardous areas

Cited by 21 publications

References 2 publications

Reliability functions for buried submarine pipelines in clay subjected to upheaval buckling

Reliability functions for buried submarine pipelines in clay subjected to upheaval buckling

Residual shear strength of fine-grained soils and soil–solid interfaces at low effective normal stresses

Modelling spatial variability in as-laid embedment for high pressure and high temperature (HPHT) pipeline design

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