Spudcan penetration analysis for three case histories in sand overlying clay

Research output: Contribution to conferenceAbstract

Abstract

The presence of problematic seabed profiles challenges the stability of the rig during spudcan installation. The typical soil profile consists of a relatively thin layer of sand, which temporarily supports the spudcan, underlain by a weak clay layer. Such soil stratigraphy is commonly found to be the main cause of spudcan punch-through, which in turn may lead to substantial damages to the leg structures. The industry guideline ISO (2012) recommends to use either a load spread method or the punching shear method to calculate the peak resistance for a spudcan on sand overlying clay, for which the failure mechanisms were based on small scale experiments. The formation and subsequent progression of the sand plug trapped below a penetrating spudcan is not considered when calculating the penetration resistance in the underlying clay layer. Therefore, the accuracy of the prediction is limited not only by the reliability of the interpreted soil strength parameters, but also by the validity of the design method currently in use. In this paper, comparisons between the methods recommended in the ISO (2012) industry guideline and the full profile prediction method of Hu et al. were made. By back-analysing two field cases, the Hu et al. method shows a significant improvement in predicting the spudcan bearing capacity-depth profile, which could not be achieved by existing methods based on a wished-in-place shallow foundation assuming a single failure mechanism applied repeatedly at different penetration depths. The Hu et al. method captures the essential characteristics of spudcan penetration behavior in sand overlying clay, which in turn enables the potential punch-through failure and the corresponding punch-through distance to be better assessed.
Original languageEnglish
Pages1-12
Number of pages12
Publication statusPublished - 2015
Event15th International Conference: The Jack-Up Platform Design, Construction & Operation - London, UK, London, United Kingdom
Duration: 15 Sep 201516 Sep 2015

Conference

Conference15th International Conference: The Jack-Up Platform Design, Construction & Operation
CountryUnited Kingdom
CityLondon
Period15/09/1516/09/15

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penetration
clay
sand
history
failure mechanism
capture method
soil strength
industry
design method
prediction
bearing capacity
soil profile
method
analysis
stratigraphy
damage
soil
experiment

Cite this

Hu, P., Cassidy, M. J., Wang, D., & Stanier, S. A. (2015). Spudcan penetration analysis for three case histories in sand overlying clay. 1-12. Abstract from 15th International Conference: The Jack-Up Platform Design, Construction & Operation, London, United Kingdom.
Hu, Pan ; Cassidy, Mark J. ; Wang, Dong ; Stanier, Sam A. / Spudcan penetration analysis for three case histories in sand overlying clay. Abstract from 15th International Conference: The Jack-Up Platform Design, Construction & Operation, London, United Kingdom.12 p.
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title = "Spudcan penetration analysis for three case histories in sand overlying clay",
abstract = "The presence of problematic seabed profiles challenges the stability of the rig during spudcan installation. The typical soil profile consists of a relatively thin layer of sand, which temporarily supports the spudcan, underlain by a weak clay layer. Such soil stratigraphy is commonly found to be the main cause of spudcan punch-through, which in turn may lead to substantial damages to the leg structures. The industry guideline ISO (2012) recommends to use either a load spread method or the punching shear method to calculate the peak resistance for a spudcan on sand overlying clay, for which the failure mechanisms were based on small scale experiments. The formation and subsequent progression of the sand plug trapped below a penetrating spudcan is not considered when calculating the penetration resistance in the underlying clay layer. Therefore, the accuracy of the prediction is limited not only by the reliability of the interpreted soil strength parameters, but also by the validity of the design method currently in use. In this paper, comparisons between the methods recommended in the ISO (2012) industry guideline and the full profile prediction method of Hu et al. were made. By back-analysing two field cases, the Hu et al. method shows a significant improvement in predicting the spudcan bearing capacity-depth profile, which could not be achieved by existing methods based on a wished-in-place shallow foundation assuming a single failure mechanism applied repeatedly at different penetration depths. The Hu et al. method captures the essential characteristics of spudcan penetration behavior in sand overlying clay, which in turn enables the potential punch-through failure and the corresponding punch-through distance to be better assessed.",
author = "Pan Hu and Cassidy, {Mark J.} and Dong Wang and Stanier, {Sam A.}",
year = "2015",
language = "English",
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note = "15th International Conference: The Jack-Up Platform Design, Construction & Operation ; Conference date: 15-09-2015 Through 16-09-2015",

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Hu, P, Cassidy, MJ, Wang, D & Stanier, SA 2015, 'Spudcan penetration analysis for three case histories in sand overlying clay' 15th International Conference: The Jack-Up Platform Design, Construction & Operation, London, United Kingdom, 15/09/15 - 16/09/15, pp. 1-12.

Spudcan penetration analysis for three case histories in sand overlying clay. / Hu, Pan; Cassidy, Mark J.; Wang, Dong; Stanier, Sam A.

2015. 1-12 Abstract from 15th International Conference: The Jack-Up Platform Design, Construction & Operation, London, United Kingdom.

Research output: Contribution to conferenceAbstract

TY - CONF

T1 - Spudcan penetration analysis for three case histories in sand overlying clay

AU - Hu, Pan

AU - Cassidy, Mark J.

AU - Wang, Dong

AU - Stanier, Sam A.

PY - 2015

Y1 - 2015

N2 - The presence of problematic seabed profiles challenges the stability of the rig during spudcan installation. The typical soil profile consists of a relatively thin layer of sand, which temporarily supports the spudcan, underlain by a weak clay layer. Such soil stratigraphy is commonly found to be the main cause of spudcan punch-through, which in turn may lead to substantial damages to the leg structures. The industry guideline ISO (2012) recommends to use either a load spread method or the punching shear method to calculate the peak resistance for a spudcan on sand overlying clay, for which the failure mechanisms were based on small scale experiments. The formation and subsequent progression of the sand plug trapped below a penetrating spudcan is not considered when calculating the penetration resistance in the underlying clay layer. Therefore, the accuracy of the prediction is limited not only by the reliability of the interpreted soil strength parameters, but also by the validity of the design method currently in use. In this paper, comparisons between the methods recommended in the ISO (2012) industry guideline and the full profile prediction method of Hu et al. were made. By back-analysing two field cases, the Hu et al. method shows a significant improvement in predicting the spudcan bearing capacity-depth profile, which could not be achieved by existing methods based on a wished-in-place shallow foundation assuming a single failure mechanism applied repeatedly at different penetration depths. The Hu et al. method captures the essential characteristics of spudcan penetration behavior in sand overlying clay, which in turn enables the potential punch-through failure and the corresponding punch-through distance to be better assessed.

AB - The presence of problematic seabed profiles challenges the stability of the rig during spudcan installation. The typical soil profile consists of a relatively thin layer of sand, which temporarily supports the spudcan, underlain by a weak clay layer. Such soil stratigraphy is commonly found to be the main cause of spudcan punch-through, which in turn may lead to substantial damages to the leg structures. The industry guideline ISO (2012) recommends to use either a load spread method or the punching shear method to calculate the peak resistance for a spudcan on sand overlying clay, for which the failure mechanisms were based on small scale experiments. The formation and subsequent progression of the sand plug trapped below a penetrating spudcan is not considered when calculating the penetration resistance in the underlying clay layer. Therefore, the accuracy of the prediction is limited not only by the reliability of the interpreted soil strength parameters, but also by the validity of the design method currently in use. In this paper, comparisons between the methods recommended in the ISO (2012) industry guideline and the full profile prediction method of Hu et al. were made. By back-analysing two field cases, the Hu et al. method shows a significant improvement in predicting the spudcan bearing capacity-depth profile, which could not be achieved by existing methods based on a wished-in-place shallow foundation assuming a single failure mechanism applied repeatedly at different penetration depths. The Hu et al. method captures the essential characteristics of spudcan penetration behavior in sand overlying clay, which in turn enables the potential punch-through failure and the corresponding punch-through distance to be better assessed.

M3 - Abstract

SP - 1

EP - 12

ER -

Hu P, Cassidy MJ, Wang D, Stanier SA. Spudcan penetration analysis for three case histories in sand overlying clay. 2015. Abstract from 15th International Conference: The Jack-Up Platform Design, Construction & Operation, London, United Kingdom.