Physical and numerical modelling of lateral buckling of a pipeline in very soft clay

2005 ◽  
Author(s):  
R Borges ◽  
M Almeida ◽  
M Almeida ◽  
J Oliveira ◽  
A Costa ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Soft Clay ◽  
Lateral Buckling

Effect of Lateral Pipe-Soil Interaction on Controlled Lateral Buckling Using Pre-Deformed Pipeline

2018 ◽  
Author(s):  
Jayden Chee ◽  
Alastair Walker ◽  
David White
Keyword(s):  
High Temperature ◽  
Longitudinal Strain ◽  
Flow Line ◽  
Soft Clay ◽  
Axial Stiffness ◽  
Lateral Buckling ◽  
Novel Approach ◽  
Different Response ◽  
Local Variability ◽  
Very High

A novel approach to eliminate the onset of global buckling in pipelines is investigated in the paper. The method is based on pre-deforming a pipeline continuously with a specific wavelength and amplitude prior to installation on the seabed. The response of the pipeline to applied high temperature and pressure was studied in conjunction with variations in the lateral pipe-soil interaction (PSI) — both as uniform friction along the pipe and also with locally varying friction. Pipe and seabed parameters representing a typical wet-insulated infield flow line on soft clay are used. The pre-deformed pipeline has a higher buckle initiation temperature compared to a straight pipeline due to the reduced effective axial force build-up resulting from the low axial stiffness generated by the pre-deformed lobes along the pipeline. The results from this paper show that the strains in the pre-deformed pipeline are not significantly affected by the local variability of lateral PSI but rather by the global mean PSI. At a typical lateral soil resistance, i.e. a friction coefficient of 0.5, lateral buckling occurs at a very high temperature level that is not common in the subsea operation. At a very low friction, i.e. 0.1, lateral buckling occurs at a lower operating temperature but the strain is insignificant. The longitudinal strain of the pipeline is not highly sensitive to the lateral PSI, which is a quite different response to an initially straight pipeline. Therefore, this method could prove to be a valuable tool for the subsea industry as it enables the pipeline to be installed and operated safely at very high temperatures without the need for lateral buckling design and installation of expensive structures as buckle initiators. Even if the pre-deformed pipeline buckles at a very high temperature, during cycles of heat-up and cool-down the buckle shape ‘shakes down’ by geometric rearrangement to minimize the energy, and in doing so creates a series of ‘short pipelines’ in which the longitudinal strain is self-controlled. The system is therefore shown to be very robust in the conditions investigated and not affected by one of the biggest unknowns in seabed pipeline engineering, which is the local variability in lateral PSI.

Numerical modelling of stone columns in soft clay under an embankment

2008 ◽  
pp. 305-311 ◽  
Author(s):  
M Gäb ◽  
H Schweiger ◽  
V Racansky ◽  
T Weber ◽  
S Springman
Keyword(s):  
Numerical Modelling ◽  
Soft Clay ◽  
Stone Columns

Feasibility Study of Lateral Buckling Using Residual Curvature Method for Deep Water Pipelines

2020 ◽  
Author(s):  
Qiang Bai ◽  
Fengbin Xu ◽  
Mark Brunner
Keyword(s):  
Deep Water ◽  
Twist Angle ◽  
Soft Clay ◽  
Soil Surface ◽  
Lateral Buckling ◽  
Finite Element Software ◽  
User Subroutine ◽  
Maximum Value ◽  
Water Pipelines ◽  
Residual Curvature

Abstract In recent years the residual curvature (RC) method has been used to provide buckle initiators to control and mitigate the lateral buckling of pipelines for some shallow water projects. With the appropriate planning of the controlled buckles using RC sections, an acceptable design of the pipeline in-place behavior is achieved. However, the RC method has not yet been applied to deep-water pipelines. The twist of RC sections in the sagbend during installation has been observed, and the orientation of as-laid RC section on the seabed is difficult to control in deep-water pipelines. The effects of as-laid RC-section orientation on in-place lateral buckling in deep water are unknown. The FRIC user subroutine in the Abaqus finite-element software suite has been developed for modelling pipe-soil interactions based on uncoupled axial and lateral soil resistances that are assumed to be independent of vertical pipe penetration after initial embedment into the soil surface. However, the penetration of a twisted RC section can vary dramatically from a normal pipeline on the seabed. The UINTER user subroutine in Abaqus was selected for presenting 3D pipe-soil interactions that incorporate the variations of independent axial and lateral soil resistances as a function of pipe penetration more accurately. UINTER is used in the present study to account for the effects of soil penetration on the lateral buckling performance of a pipeline with RC sections in soft clay. The analysis results show that the RC section twists in the sagbend area during installation, and the twist angle reaches its maximum value just prior to the RC section touching the seabed. The in-place lateral buckling analysis is carried out after the installation analysis is finished. The analysis results demonstrate the feasibility of applying the RC method as the primary buckle triggering mechanism for deep water pipelines, and it shows how the RC orientation affects the pipeline in-place performance in terms of strength and fatigue damage (only the stress ranges for use in fatigue calculations are shown in the paper).

Numerical Modelling of Pull Out Resistance of Anchored Stone Column in Soft Clay

2014 ◽  
Vol 4 (1) ◽  
pp. 29-36
Author(s):  
Chokhawala H. N ◽  
◽  
Desai. D. J ◽  
Rudani S. V. ◽  
Shah R. D ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Soft Clay ◽  
Stone Column ◽  
Pull Out

Evaluation of the Operational Behaviour of a Deepwater Oil Export Pipeline Designed on the Basis of Controlled Lateral Buckling

2011 ◽  
Author(s):  
T. Sriskandarajah ◽  
Arek Bedrossian ◽  
Graeme Roberts ◽  
Peter Tanscheit ◽  
Rafael F. Solano ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Soft Clay ◽  
Fe Model ◽  
Lateral Buckling ◽  
Design Data ◽  
Initial Design ◽  
Oil Export ◽  
Lateral Curvature ◽  
Evaluation Stage

An account is given of the methods used to evaluate the operating structural performance of a reel laid deepwater oil HP/HT pipeline which had been designed based on the controlled lateral buckling principle. The objective was to develop a finite element (FE) model of the line based on its operating status and to use the model to confirm its present and future structural integrity. The line is surface laid on a fairly undulating soft clay seabed at its deep end and sand at the shallower end. It incorporates three different man-made buckle triggering mechanisms of buoyancy modules, dual sleepers and locally increased lateral curvature along its entire length. The steps involved in the inclusion of the in-situ operating condition of the pipeline, provided through various surveys made of the as-built and operating line and historical records of operating temperatures and pressures and flow rates made at inlet and outlet of the line, into the FE model, is discussed. Several key considerations essential for the successful development and validation of such an operation-based FE model, and for completion of the evaluation task, are highlighted in the paper. Also, a specific challenge encountered as a result of changes in regulatory guidelines on engineering critical assessments, from initial design to current evaluation stage, is discussed. The evaluation has demonstrated that it is feasible to carry out in-situ assessments of laterally buckling subsea lines, and that such assessments can provide not only reliable information regarding current and future structural integrity of the lines, but also invaluable confirmation of initial design data and rationale. This comparison between initial design and the actual operating behavior of the line is not included in this paper but will be described in detail in a future separate paper.

Sign in / Sign up

Export Citation Format

Share Document