Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2009
Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implic... more Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implications and impact of their limitations on pipeline design are discussed. Alternative analysis methods are proposed to address the shortcomings of the current engineering ...
The Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) ice scour model developed in the prev... more The Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) ice scour model developed in the previous years is used to study the importance of some of the pipe, seabed soil, and scour parameters. The effect of some of these parameters on the pipeline response is investigated. The paper reveals that the influence of these parameters on the pipeline response is very different than predicted by the Winkler models and also very beneficial for the pipeline design. A pipe-in-pipe (PIP) system is analyzed using the same model. It is shown that a carrier pipe installed in a PIP system would experience stresses less than those of the same size single pipe installed in the same trench by about one order of magnitude.
A computational model illustrating the application of the ALE FE method to simulate three dimensi... more A computational model illustrating the application of the ALE FE method to simulate three dimensional debris flows is presented. The paper studies the influence of the initial and boundary conditions on the dynamics of the debris flows on simplified terrain geometry. The effects of the loading conditions and soil properties are also illustrated. The paper demonstrates the applicability and versatility of the ALE method for the debris flow problem while satisfying all the principles of continuum mechanics.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2009
Cohesive finite element model of a pile and level ice interaction is developed. It is shown that ... more Cohesive finite element model of a pile and level ice interaction is developed. It is shown that the response of such a dynamical system involves quasi-periodic and chaotic functions separated by bifurcations resulting from fracture failures or caused by the stability of ice rubble formed around the structure during the interaction. It is also illustrated that the response of such a complex and strongly nonlinear system cannot be derived from its subcomponents.
The main objective of this paper is to present a Finite Element (FE) numerical model of the ice s... more The main objective of this paper is to present a Finite Element (FE) numerical model of the ice scour process. The FE model is developed to study the soil deformation and transport process around the scouring ice and to investigate the effects of the ice scour on a pipeline buried or laid in a trench cut on the seabed. The focus of this paper is on the scours caused by ice ridges commonly observed in the Beaufort Sea. The developed FE model is a new application of the Arbitrary-Lagrangian-Eulerian (ALE) method to a soil mechanics problem involving very large deformations. Soil material, originally positioned in front of the ice ridge, is transported forward and sideways through the FE mesh and deposited in the berms formed on both sides of the scour. The soil material below the scour depth similarly moves across the mesh simulating the subscour effect. An inviscid CAP plasticity constitutive model is used to model the soil material. This paper focuses on the interaction between the ice ridge and the seabed. It describes soil transport process involved during the interaction. The soil deformation field obtained from the model is compared with the empirical deformation functions commonly used in current design methods. Future papers will report on the interaction between the ice ridge, the infill in the pipeline trench, and the pipeline; the influence of the soil properties of the trench and the seabed will also be studied.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2007
[摘要]: This paper presents an overview of the challenges in modelling ice gouge process and pipeli... more [摘要]: This paper presents an overview of the challenges in modelling ice gouge process and pipeline response to it. It discusses possible ice gouge scenarios observed in various parts of the world. It presents guidelines for the formulation of a well posed mathematical ...
ABSTRACT This book presents the papers given at a conference on offshore platforms. Topics consid... more ABSTRACT This book presents the papers given at a conference on offshore platforms. Topics considered in this book include risk assessment, crack propagation, fracture control, stress corrosion, the reliability of pile foundations, the thermal conductivity of offshore pipeline coating material, economic analysis, hydrodynamics, simulation, Arctic structure design, composite materials, buoys, deep water drilling, corrosion protection, pollution control equipment, and subsea exhaust gas compressors.
A Finite Element (FE) model of the ice scour process is developed to study the soil deformation a... more A Finite Element (FE) model of the ice scour process is developed to study the soil deformation and transport process around the scouring ice and to investigate the effects of the ice scour on pipelines buried in or installed on the seabed. The effect of the ice ridge angle and the ice scour depth on the sub-scour (boundary layer) and the ice reaction forces is analyzed. The developed FE model is an application of the Arbitrary-Lagrangian-Eulerian (ALE) method to a soil mechanics problem involving very large deformations.
International Journal of Solids and Structures, Feb 1, 2018
A general formulation for the two dimensional lateral buckling problem is developed employing cla... more A general formulation for the two dimensional lateral buckling problem is developed employing classical rod theory. A nonlinear differential system with seven unknowns is derived. Governing equations include a number of previously unaccounted nonlinear terms expressing interaction of various variables representing pipeline geometry and external loads. A rigorous derivation of the transformation of surface loads due to internal and external pressures to line loads revealed some previously unknown limitations on its applicability. Several boundary value problems are formulated corresponding to common pipeline engineering problems. Nonlinear dynamics methods are employed to draw some preliminary results on the behavior of the solutions. It is shown that the trivial solution corresponding to a perfectly straight pipeline experiencing no initial deformation and initial force is unstable.
Seabed soil deformation by grounded ice determine the forces required for scour to occur, and has... more Seabed soil deformation by grounded ice determine the forces required for scour to occur, and has important implications for pipelines. If large deformation extend deep into the ground, a pipeline might still be damaged even if it were buried below the maximum gouge depth. This paper describes an approach to the problem of determining how far below the ice the gouging deformations extend. It applies soil cutting theory and derives deformation modes from discontinuous velocity field theory developed in other areas of soil mechanics.
Journal of Energy Resources Technology-transactions of The Asme, Mar 1, 1982
Several three-dimensional pipeline problems are used to illustrate a general pipeline and riser m... more Several three-dimensional pipeline problems are used to illustrate a general pipeline and riser model with twist. A continuation technique is developed to solve convergence problems. Suitable stiff numerical methods are reviewed for general applications.
International Journal of Solids and Structures, Feb 1, 2018
A general formulation for the two dimensional lateral buckling problem is developed employing cla... more A general formulation for the two dimensional lateral buckling problem is developed employing classical rod theory. A nonlinear differential system with seven unknowns is derived. Governing equations include a number of previously unaccounted nonlinear terms expressing interaction of various variables representing pipeline geometry and external loads. A rigorous derivation of the transformation of surface loads due to internal and external pressures to line loads revealed some previously unknown limitations on its applicability. Several boundary value problems are formulated corresponding to common pipeline engineering problems. Nonlinear dynamics methods are employed to draw some preliminary results on the behavior of the solutions. It is shown that the trivial solution corresponding to a perfectly straight pipeline experiencing no initial deformation and initial force is unstable.
A new Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) model of ice scour was recently dev... more A new Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) model of ice scour was recently developed by the authors. It is based on continuum representation of the soil. It was shown in recent papers that such a model can characterize the mechanics of the ice-soil-pipeline interaction without requiring any of the assumptions that the Winkler models depend on. The model utilizes soil properties obtained by conventional laboratory testing. In a recent paper, this model was used to show that the subscour deformations and ice-soil interaction forces are very sensitive to ice ridge geometries for shallow slope ice features. In this paper, the ALE FE ice scour model is utilized to study the effects of the pipeline trench on the scour process and the forces transmitted to the pipeline. Two different infill soil properties and two different ice ridge geometries are analyzed with a 36 inch diameter pipe buried to in a trench of 1.5 m cover.
Journal of Energy Resources Technology-transactions of The Asme, Dec 1, 1980
A unified three-dimensional formulation of the pipeline or riser problems is developed by followi... more A unified three-dimensional formulation of the pipeline or riser problems is developed by following the rod theories. A rigorous singular perturbation technique is used to solve the associated two-dimensional nonlinear problem. The results can be used with a programmable calculator.
Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implic... more Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implications and impact of their limitations on pipeline design are discussed. Alternative analysis methods are proposed to address the shortcomings of the current engineering ...
A framework incorporating dynamic crack propagation and continuum mechanics for modeling ice-stru... more A framework incorporating dynamic crack propagation and continuum mechanics for modeling ice-structure interaction processes is developed. The framework is build upon a comprehensive review of recent developments in the analysis of dynamic fragmentation problems for materials such as ceramics, concrete, and metals. A review of alternative crack propagation modeling methods is also included in order to illustrate how the developed framework may overcome the shortcomings of existing techniques. This is the first paper (Part I) in a series of three papers. The formulation of the framework is presented in this paper. In the second paper (Part II), implementation of the framework will be described. The application of the framework to various ice-structure interaction problems will be presented in Part III along with the demonstration and investigation of important aspects of these scenarios.
The general framework for a cohesive finite element model for the analysis of ice-structure inter... more The general framework for a cohesive finite element model for the analysis of ice-structure interaction problems incorporating plasticity and fracture was presented at OMAE 2009 as Parts I & II. This third paper presents the application of the framework to various ice-structure interaction problems. It investigates the important aspects of these scenarios and reveals their characteristics which may play a major role in the design of structures. The investigations include the geometry, size and velocity effects as well as the influence of the structure stiffness. The paper also studies the effects of ice characteristics, and interaction speeds.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2009
Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implic... more Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implications and impact of their limitations on pipeline design are discussed. Alternative analysis methods are proposed to address the shortcomings of the current engineering ...
The Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) ice scour model developed in the prev... more The Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) ice scour model developed in the previous years is used to study the importance of some of the pipe, seabed soil, and scour parameters. The effect of some of these parameters on the pipeline response is investigated. The paper reveals that the influence of these parameters on the pipeline response is very different than predicted by the Winkler models and also very beneficial for the pipeline design. A pipe-in-pipe (PIP) system is analyzed using the same model. It is shown that a carrier pipe installed in a PIP system would experience stresses less than those of the same size single pipe installed in the same trench by about one order of magnitude.
A computational model illustrating the application of the ALE FE method to simulate three dimensi... more A computational model illustrating the application of the ALE FE method to simulate three dimensional debris flows is presented. The paper studies the influence of the initial and boundary conditions on the dynamics of the debris flows on simplified terrain geometry. The effects of the loading conditions and soil properties are also illustrated. The paper demonstrates the applicability and versatility of the ALE method for the debris flow problem while satisfying all the principles of continuum mechanics.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2009
Cohesive finite element model of a pile and level ice interaction is developed. It is shown that ... more Cohesive finite element model of a pile and level ice interaction is developed. It is shown that the response of such a dynamical system involves quasi-periodic and chaotic functions separated by bifurcations resulting from fracture failures or caused by the stability of ice rubble formed around the structure during the interaction. It is also illustrated that the response of such a complex and strongly nonlinear system cannot be derived from its subcomponents.
The main objective of this paper is to present a Finite Element (FE) numerical model of the ice s... more The main objective of this paper is to present a Finite Element (FE) numerical model of the ice scour process. The FE model is developed to study the soil deformation and transport process around the scouring ice and to investigate the effects of the ice scour on a pipeline buried or laid in a trench cut on the seabed. The focus of this paper is on the scours caused by ice ridges commonly observed in the Beaufort Sea. The developed FE model is a new application of the Arbitrary-Lagrangian-Eulerian (ALE) method to a soil mechanics problem involving very large deformations. Soil material, originally positioned in front of the ice ridge, is transported forward and sideways through the FE mesh and deposited in the berms formed on both sides of the scour. The soil material below the scour depth similarly moves across the mesh simulating the subscour effect. An inviscid CAP plasticity constitutive model is used to model the soil material. This paper focuses on the interaction between the ice ridge and the seabed. It describes soil transport process involved during the interaction. The soil deformation field obtained from the model is compared with the empirical deformation functions commonly used in current design methods. Future papers will report on the interaction between the ice ridge, the infill in the pipeline trench, and the pipeline; the influence of the soil properties of the trench and the seabed will also be studied.
Proceedings of the International Conference on Port and Ocean Engineering Under Arctic Conditions, 2007
[摘要]: This paper presents an overview of the challenges in modelling ice gouge process and pipeli... more [摘要]: This paper presents an overview of the challenges in modelling ice gouge process and pipeline response to it. It discusses possible ice gouge scenarios observed in various parts of the world. It presents guidelines for the formulation of a well posed mathematical ...
ABSTRACT This book presents the papers given at a conference on offshore platforms. Topics consid... more ABSTRACT This book presents the papers given at a conference on offshore platforms. Topics considered in this book include risk assessment, crack propagation, fracture control, stress corrosion, the reliability of pile foundations, the thermal conductivity of offshore pipeline coating material, economic analysis, hydrodynamics, simulation, Arctic structure design, composite materials, buoys, deep water drilling, corrosion protection, pollution control equipment, and subsea exhaust gas compressors.
A Finite Element (FE) model of the ice scour process is developed to study the soil deformation a... more A Finite Element (FE) model of the ice scour process is developed to study the soil deformation and transport process around the scouring ice and to investigate the effects of the ice scour on pipelines buried in or installed on the seabed. The effect of the ice ridge angle and the ice scour depth on the sub-scour (boundary layer) and the ice reaction forces is analyzed. The developed FE model is an application of the Arbitrary-Lagrangian-Eulerian (ALE) method to a soil mechanics problem involving very large deformations.
International Journal of Solids and Structures, Feb 1, 2018
A general formulation for the two dimensional lateral buckling problem is developed employing cla... more A general formulation for the two dimensional lateral buckling problem is developed employing classical rod theory. A nonlinear differential system with seven unknowns is derived. Governing equations include a number of previously unaccounted nonlinear terms expressing interaction of various variables representing pipeline geometry and external loads. A rigorous derivation of the transformation of surface loads due to internal and external pressures to line loads revealed some previously unknown limitations on its applicability. Several boundary value problems are formulated corresponding to common pipeline engineering problems. Nonlinear dynamics methods are employed to draw some preliminary results on the behavior of the solutions. It is shown that the trivial solution corresponding to a perfectly straight pipeline experiencing no initial deformation and initial force is unstable.
Seabed soil deformation by grounded ice determine the forces required for scour to occur, and has... more Seabed soil deformation by grounded ice determine the forces required for scour to occur, and has important implications for pipelines. If large deformation extend deep into the ground, a pipeline might still be damaged even if it were buried below the maximum gouge depth. This paper describes an approach to the problem of determining how far below the ice the gouging deformations extend. It applies soil cutting theory and derives deformation modes from discontinuous velocity field theory developed in other areas of soil mechanics.
Journal of Energy Resources Technology-transactions of The Asme, Mar 1, 1982
Several three-dimensional pipeline problems are used to illustrate a general pipeline and riser m... more Several three-dimensional pipeline problems are used to illustrate a general pipeline and riser model with twist. A continuation technique is developed to solve convergence problems. Suitable stiff numerical methods are reviewed for general applications.
International Journal of Solids and Structures, Feb 1, 2018
A general formulation for the two dimensional lateral buckling problem is developed employing cla... more A general formulation for the two dimensional lateral buckling problem is developed employing classical rod theory. A nonlinear differential system with seven unknowns is derived. Governing equations include a number of previously unaccounted nonlinear terms expressing interaction of various variables representing pipeline geometry and external loads. A rigorous derivation of the transformation of surface loads due to internal and external pressures to line loads revealed some previously unknown limitations on its applicability. Several boundary value problems are formulated corresponding to common pipeline engineering problems. Nonlinear dynamics methods are employed to draw some preliminary results on the behavior of the solutions. It is shown that the trivial solution corresponding to a perfectly straight pipeline experiencing no initial deformation and initial force is unstable.
A new Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) model of ice scour was recently dev... more A new Arbitrary Lagrangian Eulerian (ALE) Finite Element (FE) model of ice scour was recently developed by the authors. It is based on continuum representation of the soil. It was shown in recent papers that such a model can characterize the mechanics of the ice-soil-pipeline interaction without requiring any of the assumptions that the Winkler models depend on. The model utilizes soil properties obtained by conventional laboratory testing. In a recent paper, this model was used to show that the subscour deformations and ice-soil interaction forces are very sensitive to ice ridge geometries for shallow slope ice features. In this paper, the ALE FE ice scour model is utilized to study the effects of the pipeline trench on the scour process and the forces transmitted to the pipeline. Two different infill soil properties and two different ice ridge geometries are analyzed with a 36 inch diameter pipe buried to in a trench of 1.5 m cover.
Journal of Energy Resources Technology-transactions of The Asme, Dec 1, 1980
A unified three-dimensional formulation of the pipeline or riser problems is developed by followi... more A unified three-dimensional formulation of the pipeline or riser problems is developed by following the rod theories. A rigorous singular perturbation technique is used to solve the associated two-dimensional nonlinear problem. The results can be used with a programmable calculator.
Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implic... more Analysis methods used for the design of offshore pipelines against ice scour are reviewed. Implications and impact of their limitations on pipeline design are discussed. Alternative analysis methods are proposed to address the shortcomings of the current engineering ...
A framework incorporating dynamic crack propagation and continuum mechanics for modeling ice-stru... more A framework incorporating dynamic crack propagation and continuum mechanics for modeling ice-structure interaction processes is developed. The framework is build upon a comprehensive review of recent developments in the analysis of dynamic fragmentation problems for materials such as ceramics, concrete, and metals. A review of alternative crack propagation modeling methods is also included in order to illustrate how the developed framework may overcome the shortcomings of existing techniques. This is the first paper (Part I) in a series of three papers. The formulation of the framework is presented in this paper. In the second paper (Part II), implementation of the framework will be described. The application of the framework to various ice-structure interaction problems will be presented in Part III along with the demonstration and investigation of important aspects of these scenarios.
The general framework for a cohesive finite element model for the analysis of ice-structure inter... more The general framework for a cohesive finite element model for the analysis of ice-structure interaction problems incorporating plasticity and fracture was presented at OMAE 2009 as Parts I & II. This third paper presents the application of the framework to various ice-structure interaction problems. It investigates the important aspects of these scenarios and reveals their characteristics which may play a major role in the design of structures. The investigations include the geometry, size and velocity effects as well as the influence of the structure stiffness. The paper also studies the effects of ice characteristics, and interaction speeds.
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