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Bw Byrne - One of the best experts on this subject based on the ideXlab platform.
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Suction Caissons in dense sand, Part II: Vertical cyclic loading into tension
'Thomas Telford Ltd.', 2018Co-Authors: Bienen B, Rt Klinkvort, O'loughlin C, Zhu F, Bw ByrneAbstract:Suction Caissons have been used for numerous oil and gas installations and are increasingly considered as a foundation solution for offshore wind turbines (OWT). There can be significant differences between the two offshore energy applications in the load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). This paper investigates the response of suction Caissons in dense sand to a range of cyclic vertical loading histories relevant to a jacket supported OWT, with an emphasis on cyclic tensile loading. The findings are based on a series of experiments performed in a centrifuge, such that soil stresses reflect those in the prototype. The Caisson was installed using suction at enhanced gravity, followed by cyclic loading and then Caisson extraction. The installation and extraction results are discussed in a companion paper. This paper focuses on the Caisson load-displacement response under vertical cyclic loading. The centrifuge experimental results reinforce findings from previous work, add insights into the load transfer mechanisms and provide confidence of their applicability to the prototype, both qualitatively and quantitatively. The results highlight the complexity of the Caisson response, particularly under tensile loading, with the influences of average load, cyclic load amplitude, and drainage discussed in detail
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Suction Caissons in dense sand, part I: installation, limiting capacity and drainage
'Thomas Telford Ltd.', 2018Co-Authors: Bienen B, Rt Klinkvort, O'loughlin C, Zhu F, Bw ByrneAbstract:Suction Caissons are a promising foundation concept for supporting offshore wind turbines. Compared to applications in the oil and gas industry, where most practical experience exists, significant differences arise in terms of load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). In a set of two companion papers, this contribution investigates the response of suction Caissons in dense sand through a series of centrifuge experiments. The Caisson was installed using suction, followed by sequences of cyclic loading and then extraction, all steps completed continuously in- flight. This first paper discusses installation, limiting capacities and drainage, whereas the second paper focuses on vertical cyclic loading into tension. The work demonstrates that suction Caisson installation behaviour is well described by existing calculation methods. Tests performed at different installation rates demonstrate that careful assessment of the pumping rate is needed to ensure successful installation, with low pumping rates resulting in premature refusal. In the centrifuge tests, full skirt penetration was achieved without apparent loosening of the soil plug. The limiting capacity in tension, measured during the testing at both fast and slow uplift rates, was also well described by existing calculation methods
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Design procedures for installation of suction Caissons in clay and other materials
'Thomas Telford Ltd.', 2005Co-Authors: Guy T. Houlsby, Bw ByrneAbstract:Suction-installed skirted foundations, often referred to as suction Caissons, are increasingly being used for a variety of offshore applications. In designing a Caisson a geotechnical engineer must consider the installation process as well as the in-place performance. The purpose of this paper is to present calculation procedures for the installation of a Caisson in clay. For clay sites, the Caisson will often be used as an anchor, with the ratio of the skirt length (L) to the diameter (D) as high as 5. Calculation methods are presented for determining the resistance to penetration of open-ended cylindrical Caisson foundations with and without the application of suction inside the Caisson. Comparisons between predictions and case records are made. A companion paper describes the calculation procedure for installation in sand soils. Finally, comments are made here about installation in a variety of soils other than homogeneous deposits of clay or sand
Mostafa Zeinoddini - One of the best experts on this subject based on the ideXlab platform.
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Wall slope effects on the vertical pull-out capacity of tapered suction Caissons
Scientia Iranica, 2011Co-Authors: Mostafa Zeinoddini, J. Keyvani, Mahmood NabipourAbstract:Abstract Suction Caissons offer certain advantages over other underwater foundation systems by virtue of large bearing capacity, ease of installation, and efficiency. They are typically built with upright walls. The behaviour of upright suction Caissons in regard to their applications, installation, load-bearing, etc. has already been investigated by a number of researchers. However, the performance of tapered suction Caissons has not been formerly studied. This paper addresses the pull-out capacity of tapered suction Caissons under vertical pull-out loads. A numerical approach was used. The finite element model was first calibrated against available test results on upright suction Caissons and then used to simulate the pull-out of tapered Caissons. It is admitted, however, that further validation of the model against experimental results on tapered suction Caissons will increase the acceptability of the results. It was observed that positive wall slopes may noticeably improve the pull-out capacity. A change from local to global failure modes was postulated as the main reason for this improved resistance. With negative wall slopes, however, the pull-out capacity slightly decreased. In addition, effects from the Caisson wall slope were investigated for a number of Caisson geometries, drainage conditions and soil properties.
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On Penetration of Upright and Tapered Suction Caissons in Sand: An Experimental Study
29th International Conference on Ocean Offshore and Arctic Engineering: Volume 1, 2010Co-Authors: Siamak Kakasoltani, Mostafa Zeinoddini, Mahmoud R. Abdi, Seyyed Abbas Mousavi BehnamAbstract:Over the past two decades, suction Caissons have been increasingly utilized as deep water anchors for floating structures, foundations of offshore wind turbines and even for jacket platforms. They penetrate into the sea bed by a combination of their buoyant weight and under base suction. Suction Caissons have appeared as an efficient and economic alternative for foundations in the offshore industry. This concept, however, is relatively new, so the knowledge about their behavior has not yet gone far deep as that for other offshore foundation solutions such as driven pile systems. This paper reports some results from an experimental investigation into the installation of upright and tapered suction Caissons. The 1g experiments have been carried out on eight small scale suction Caissons. The aspect ratios, (the Caisson length/its diameter) have been 1, 2, 3 and 4. The diameter has been constant and equal to 80 mm. Four specimens have had upright walls while the other four had a positive wall slope of 10%. The Caissons have been installed in a soil tank containing very fine saturated silty sand. The penetration has been achieved under forced driving using a constant penetration rate. The effects of geometrical parameters and the soil density on the overall penetration force have been studied. it has been observed that, with both the upright and tapered Caissons, the required force for full penetration increases by an increase in the aspect ratio. The penetration force required for full penetration of tapered models, has been two to three times higher than an equivalent upright Caisson. With tapered Caissons, the penetration forces have been found to be more sensitive to the soil density as compared to that with upright Caissons. The experimental results for upright suction Caissons have also been compared with a closed form analytical solution proposed by other researchers.Copyright © 2010 by ASME
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A PARAMETRIC STUDY ON THE PULL-OUT RESPONSE OF SUCTION CaissonS
2009Co-Authors: Mostafa Zeinoddini, Mahmood NabipourAbstract:Suction Caisson foundation systems have been successfully used in the past two decades in numerous occasions on a variety of offshore structures in a wide range of environments. The pull-out capacity of suction Caissons remains a critical issue in their applications, and reliable methods of predicting the capacity are required in order to produce effective designs. In the current study a numerical approach has been chosen to investigate the behavior of suction Caissons under pull-out loads. The model has first been calibrated against available experimental data and also been verified against other test data. The verified model has then been used to study the influence of a number of parameters on the pull-out behavior of suction Caissons. Variations in the soil type, soil cohesion, internal friction angle, dilatancy angle, Poisson’s ratio and the aspect ratio of the Caisson have been studied. Soil nonlinearities, soil/Caisson interactions, drainage conditions and suction effects have also been taken into consideration. Simple approximations have been put forward to express the effects from above mentioned different parameters on the pull-out capacity. These approximations have also been compared
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Feasibility of Suction Caisson Solutions for the Foundations of Offshore Jacket Platforms in the Persian Gulf
Volume 2: Structures Safety and Reliability, 2008Co-Authors: Mostafa Zeinoddini, B. Saeidi, G. A. R. ParkeAbstract:This paper gives the results of an investigation into the performance of the suction Caisson foundations for jacket platforms in the Persian Gulf under quasi static environmental wave loading. A numerical approach has been chosen to study the subject. The installation phase has not been analysed, so the suction Caisson foundations have been considered in an in situ condition. At first, three dimensional finite element models of the suction Caissons, embedded in the sea bed but in isolation of the jacket, have been examined under static vertical, horizontal and inclined loadings. The results have been verified against available test data from other researchers and, in general, reasonable agreements have been obtained between the numerical and the experimental results. The models of some of the existing jacket structure in the Persian Gulf have then been incorporated with the verified Caisson models. The resulting integrated model of the jacket/Caissons/soil body has been examined under push-over environmental loads. The results have then been assessed against those obtained from the corresponding jackets with driven pile foundations. From the current study, the suction Caisson foundations have been found to be able to contest the deep pile foundation solution due to savings in the material utilization costs and their load carrying capacity.Copyright © 2008 by ASME
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Numerical investigation on tapering effects on the pull-out capacity of suction Caissons in clay
2007Co-Authors: Mostafa Zeinoddini, Mahmood Nabipour, J. KeyvaniAbstract:Suction Caissons, as an innovative underwater foundation system, have been successfully used in numerous occasions on a variety of offshore structures. Different researchers have investigated the pullout behaviour of suction Caissons using experimental, analytical and numerical approaches. They have studied only upright suction Caissons and the behaviour of tapered suction Caissons has not formerly been noticed to any degrees. In this paper the pull-out capacity of tapered suction Caissons in clay has been numerically investigated. The numerical models have first been calibrated and verified against available experimental data in the literature for upright suction Caissons. The verified models have then been employed to examine the effects from the wall tapering on the Caisson pull-out capacity. Only vertical pull-out loads have been examined. Numerical results indicate that tapered Caissons present considerable enhancement in their pull-out capacity comparing to those from corresponding upright Caissons. This enhancement can reach to several orders of the pull-out capacity of their equivalent upright Caisson even with small values of Caisson tapering. An almost linear rate of enhancement has been observed between the wall slope and the pull-out capacity of suction Caisson. This rate of enhancement increases significantly by the increase in the Caisson length. In general higher rates of enhancement to the pull-out capacity due to wall sloping have been observed under drained conditions compared to those obtained under undrained conditions.
M. Sri Krishna - One of the best experts on this subject based on the ideXlab platform.
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Design Analysis of Moored Floating Caisson System
Journal of Offshore Mechanics and Arctic Engineering, 2004Co-Authors: Partha Chakrabarti, Subrata K. Chakrabarti, Adinarayana Mukkamala, Nagaraj Anavekar, Shen Qiang, M. Sri KrishnaAbstract:Tacoma Narrows Constructors (TNC) are building a new suspension bridge in Tacoma, close to Seattle, Washington State, USA. The new bridge is being built just south of the existing bridge mounted on two Caissons. The Caissons are constructed on location after the shallow draft Caissons are towed to site. During the construction sequence, the mooring system for each Caisson consists of two sets of 16 mooring lines. The lower 16 lines are hooked-up after the shallow draft Caisson is towed from the harbor and positioned at the site. The fairlead locations for these lines are kept constant throughout the construction process. The fairlead locations for the upper 16 lines (except three lines on the East Caisson) vary based on the Caisson draft. The Caissons are subject to a high current from the ebb and flood tide flow in the Narrows. The new Caissons are in close proximity to the existing piers and the bottom topography at the site is varying. Therefore, considerable turbulence and vortex shedding is expected in the prevailing current, which will cause current-induced dynamic forces on the Caissons. This paper describes the design and analysis of this multiline mooring system for Tacoma Narrows Bridge Caissons, based on the construction sequence in the floating condition. The analysis involved optimizing the anchor locations and the line pretensions, determining the dynamic motions of the Caissons, the maximum line loads, and the corresponding safety factors. The paper also describes the hydrodynamic analysis for added mass, and damping, the methodology used for the nonlinear moored Caisson analysis (MOTSIM), and the validation of the design tool with other similar models (e.g., STRUCAD*3D). The results of the analysis and the design of the system are discussed.
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Overview of Tacoma Narrows Bridge Floating Caisson Design
23rd International Conference on Offshore Mechanics and Arctic Engineering Volume 1 Parts A and B, 2004Co-Authors: M. Sri Krishna, Partha Chakrabarti, Subrata K. Chakrabarti, Adinarayana Mukkamala, Nagaraj AnavekarAbstract:Tacoma Narrows Constructors is building a new suspension bridge in Tacoma, close to Seattle, Washington State, USA next to an existing bridge at the location. The new bridge is being built just south of the existing bridge. This new bridge will be built on towers mounted on two Caissons. The Caissons are towed to the site from the harbor with the cutting edge, first full lift, and the second and third exterior lifts. The piers are constructed on site up to their full height as floating Caissons at varying drafts. During the construction, the floating Caissons on both ends of the new bridge are moored in place with 32 catenary mooring lines. The current flow due to ebb and flood tide in the narrows is very high. This high current and the consequent vortex-induced dynamic forces provided a technical challenge in the design of the Caisson and its mooring system whose dimensions are of similar order of magnitude as typical offshore structures exposed to severe environment. This paper provides an overview of this challenge, and describes the steps taken in overcoming these difficulties. The design procedure adopted of the moored Caisson system and the piers in the overall scheme of the Tacoma Narrows Bridge are summarized. This overview stresses the practical side of towing, mooring and in place construction of the Caissons. Some of the critical areas of associated design challenges and their solution techniques are highlighted.
Byrne B.w. - One of the best experts on this subject based on the ideXlab platform.
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Suction Caissons in dense sand, Part II: Vertical cyclic loading into tension
'Thomas Telford Ltd.', 2018Co-Authors: Bienen Britta, Zhu F, Klinkvort, Rasmus Tofte, O’loughlin C., Byrne B.w.Abstract:Suction Caissons have been used for numerous oil and gas installations and are increasingly considered as a foundation solution for offshore wind turbines (OWT). There can be significant differences between the two offshore energy applications in the load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). This paper investigates the response of suction Caissons in dense sand to a range of cyclic vertical loading histories relevant to a jacket supported OWT, with an emphasis on cyclic tensile loading. The findings are based on a series of experiments performed in a centrifuge, such that soil stresses reflect those in the prototype. The Caisson was installed using suction at enhanced gravity, followed by cyclic loading and then Caisson extraction. The installation and extraction results are discussed in a companion paper. This paper focuses on the Caisson load-displacement response under vertical cyclic loading. The centrifuge experimental results reinforce findings from previous work, add insights into the load transfer mechanisms and provide confidence of their applicability to the prototype, both qualitatively and quantitatively. The results highlight the complexity of the Caisson response, particularly under tensile loading, with the influences of average load, cyclic load amplitude, and drainage discussed in detail.acceptedVersio
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Suction Caissons in dense sand, Part I: Installation, limiting capacity and drainage
'Thomas Telford Ltd.', 2018Co-Authors: Bienen Britta, Zhu F, Klinkvort, Rasmus Tofte, O’loughlin C., Byrne B.w.Abstract:Suction Caissons are a promising foundation concept for supporting offshore wind turbines. Compared to applications in the oil and gas industry, where most practical experience exists, significant differences arise in terms of load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). In a set of two companion papers, this contribution investigates the response of suction Caissons in dense sand through a series of centrifuge experiments. The Caisson was installed using suction, followed by sequences of cyclic loading and then extraction, all steps completed continuously in-flight. This first paper discusses installation, limiting capacities and drainage, whereas the second paper focuses on vertical cyclic loading into tension. The work demonstrates that suction Caisson installation behaviour is well described by existing calculation methods. Tests performed at different installation rates demonstrate that careful assessment of the pumping rate is needed to ensure successful installation, with low pumping rates resulting in premature refusal. In the centrifuge tests, full skirt penetration was achieved without apparent loosening of the soil plug. The limiting capacity in tension, measured during the testing at both fast and slow uplift rates, was also well described by existing calculation methods.acceptedVersio
Zhu F - One of the best experts on this subject based on the ideXlab platform.
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Suction Caissons in dense sand, Part II: Vertical cyclic loading into tension
'Thomas Telford Ltd.', 2018Co-Authors: Bienen B, Rt Klinkvort, O'loughlin C, Zhu F, Bw ByrneAbstract:Suction Caissons have been used for numerous oil and gas installations and are increasingly considered as a foundation solution for offshore wind turbines (OWT). There can be significant differences between the two offshore energy applications in the load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). This paper investigates the response of suction Caissons in dense sand to a range of cyclic vertical loading histories relevant to a jacket supported OWT, with an emphasis on cyclic tensile loading. The findings are based on a series of experiments performed in a centrifuge, such that soil stresses reflect those in the prototype. The Caisson was installed using suction at enhanced gravity, followed by cyclic loading and then Caisson extraction. The installation and extraction results are discussed in a companion paper. This paper focuses on the Caisson load-displacement response under vertical cyclic loading. The centrifuge experimental results reinforce findings from previous work, add insights into the load transfer mechanisms and provide confidence of their applicability to the prototype, both qualitatively and quantitatively. The results highlight the complexity of the Caisson response, particularly under tensile loading, with the influences of average load, cyclic load amplitude, and drainage discussed in detail
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Suction Caissons in dense sand, Part II: Vertical cyclic loading into tension
'Thomas Telford Ltd.', 2018Co-Authors: Bienen Britta, Zhu F, Klinkvort, Rasmus Tofte, O’loughlin C., Byrne B.w.Abstract:Suction Caissons have been used for numerous oil and gas installations and are increasingly considered as a foundation solution for offshore wind turbines (OWT). There can be significant differences between the two offshore energy applications in the load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). This paper investigates the response of suction Caissons in dense sand to a range of cyclic vertical loading histories relevant to a jacket supported OWT, with an emphasis on cyclic tensile loading. The findings are based on a series of experiments performed in a centrifuge, such that soil stresses reflect those in the prototype. The Caisson was installed using suction at enhanced gravity, followed by cyclic loading and then Caisson extraction. The installation and extraction results are discussed in a companion paper. This paper focuses on the Caisson load-displacement response under vertical cyclic loading. The centrifuge experimental results reinforce findings from previous work, add insights into the load transfer mechanisms and provide confidence of their applicability to the prototype, both qualitatively and quantitatively. The results highlight the complexity of the Caisson response, particularly under tensile loading, with the influences of average load, cyclic load amplitude, and drainage discussed in detail.acceptedVersio
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Suction Caissons in dense sand, part I: installation, limiting capacity and drainage
'Thomas Telford Ltd.', 2018Co-Authors: Bienen B, Rt Klinkvort, O'loughlin C, Zhu F, Bw ByrneAbstract:Suction Caissons are a promising foundation concept for supporting offshore wind turbines. Compared to applications in the oil and gas industry, where most practical experience exists, significant differences arise in terms of load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). In a set of two companion papers, this contribution investigates the response of suction Caissons in dense sand through a series of centrifuge experiments. The Caisson was installed using suction, followed by sequences of cyclic loading and then extraction, all steps completed continuously in- flight. This first paper discusses installation, limiting capacities and drainage, whereas the second paper focuses on vertical cyclic loading into tension. The work demonstrates that suction Caisson installation behaviour is well described by existing calculation methods. Tests performed at different installation rates demonstrate that careful assessment of the pumping rate is needed to ensure successful installation, with low pumping rates resulting in premature refusal. In the centrifuge tests, full skirt penetration was achieved without apparent loosening of the soil plug. The limiting capacity in tension, measured during the testing at both fast and slow uplift rates, was also well described by existing calculation methods
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Suction Caissons in dense sand, Part I: Installation, limiting capacity and drainage
'Thomas Telford Ltd.', 2018Co-Authors: Bienen Britta, Zhu F, Klinkvort, Rasmus Tofte, O’loughlin C., Byrne B.w.Abstract:Suction Caissons are a promising foundation concept for supporting offshore wind turbines. Compared to applications in the oil and gas industry, where most practical experience exists, significant differences arise in terms of load paths and magnitudes, soil type and Caisson aspect ratio (skirt length to diameter). In a set of two companion papers, this contribution investigates the response of suction Caissons in dense sand through a series of centrifuge experiments. The Caisson was installed using suction, followed by sequences of cyclic loading and then extraction, all steps completed continuously in-flight. This first paper discusses installation, limiting capacities and drainage, whereas the second paper focuses on vertical cyclic loading into tension. The work demonstrates that suction Caisson installation behaviour is well described by existing calculation methods. Tests performed at different installation rates demonstrate that careful assessment of the pumping rate is needed to ensure successful installation, with low pumping rates resulting in premature refusal. In the centrifuge tests, full skirt penetration was achieved without apparent loosening of the soil plug. The limiting capacity in tension, measured during the testing at both fast and slow uplift rates, was also well described by existing calculation methods.acceptedVersio
