Pipeline Response to Slope Movement and Evaluation of Pipeline Strain Demand

2014 ◽  
Author(s):  
Abdelfettah Fredj ◽  
Aaron Dinovitzer
Keyword(s):  
Slope Failure ◽  
Smooth Particle Hydrodynamic ◽  
Slope Movement ◽  
Soil Conditions ◽  
Burial Depth ◽  
Design Standards ◽  
Element Analysis ◽  
Modeling Tools ◽  
Soil Movement ◽  
Codes Of Practice

Pipelines installed on active slopes can be exposed to slope failure mechanisms. The soil movement can introduce substantial axial and bending strains on buried pipeline, and possibly damage. The techniques to predict pipeline displacements, loads, stress or strains are not well described in design standards or codes of practice. The practice of using finite element analysis of soil-pipe interaction has developed in recent years and is proving to be a useful tool in evaluating the pipeline behavior in response to slope movement. A description of advanced pipe soil interaction modeling tools and their validation against full scale trails has been previously presented. This paper describes the ongoing work involved in a study investigating the mechanical behavior of buried pipelines interacting with active slope movement and evaluation of pipeline strain demand. Detailed pipe-soil interaction analyses were completed with a 3D continuum SPH (Smooth Particle Hydrodynamic) model to examine the pipeline behavior and evaluate the pipeline strain demand in relation to key parameters. This includes the effect of soil movement mechanism, pipeline geometry (D/t), material grade, pipeline burial depth and soil conditions and properties. Sample results of the application of the validated 3D continuum modeling process will be presented. The strain demand determined from the analyses were compared with calculated CSA-Z662 strain limit design, local FEA analyses and BS 7910. These results are being used to develop generalized trends in pipeline response to slope movements.

Simulation of the Response of Buried Pipelines to Slope Movement Using 3D Continuum Modeling

2012 ◽  
Author(s):  
Abdelfettah Fredj ◽  
Aaron Dinovitzer
Keyword(s):  
Fluid Pressure ◽  
Slope Movement ◽  
Ground Movement ◽  
Ground Subsidence ◽  
Continuum Modeling ◽  
Buried Pipelines ◽  
Design Standards ◽  
Codes Of Practice ◽  
Modeling Process ◽  
Ongoing Work

Pipeline integrity is affected by the action of external soil loads in addition to internal fluid pressure. External soil loads can be generated by landslides or at sites subject to ground subsidence, heave or seismic effects. Under these varied conditions of ground movement potential pipeline safety involves constraints on design and operations. The design processes includes developing an understanding of strains that could be imposed on the pipe (strain demand) and strain limits that the pipe can withstand without failure. The ability to predict the pipeline load, stress or strains state in the presence of soil restraint and/or soil displacement induced loading is not well described in design standards or codes of practice. This paper describes the ongoing work involved in a study investigating the mechanical behavior of buried pipelines interacting with active landslides. Detailed pipe-soil interaction analyses were completed with a 3D continuum SPH method. This paper describes the LS-DYNA numerical modeling process, previously developed by the authors, which was refined and applied to site-specific conditions. To illustrate the performance of the modeling process to consider a translational slide, additional numerical model validation was completed and is described in this paper. These comparisons illustrate that good agreement was observed between the modeling results and experimental full scale trial results. Sample results of the application of the validated 3D continuum modeling process are presented. These results are being used to develop generalized trends in pipeline response to slope movements. The paper describes both the progress achieved to date and the future potential for simplified engineering design tools to assess the load or deformation capacity requirements of buried pipelines exposed to different types of slope movement.

Multi Tiered Approach to Slope Movement Management: Case Study

2012 ◽  
Author(s):  
Millan Sen ◽  
John Richmond ◽  
Aaron Dinovitzer ◽  
Abdelfettah Fredj
Keyword(s):  
Stress Analysis ◽  
Slope Failure ◽  
Action Plan ◽  
Large Diameter ◽  
Mass Movement ◽  
Strain Analysis ◽  
Slope Movement ◽  
Soil Movement ◽  
Slope Movements ◽  
Inspection Data

A major slope in southern Manitoba is currently experiencing deep seated movements of approximately 60mm per year. This 20m high × 70m long slope contains a pipeline right of way with five large diameter crude oil lines that were constructed from 1950–1998. It is estimated that the slope has moved over 3 meters since the pipeline installations. Management of the effects of this slope movement on the pipelines has involved cross-functional strategies that include geotechnical, integrity, and stress evaluations. The slope is assessed annually by a geotechnical engineer, and the most likely cause for the slope movements has been determined. Slope monitoring equipment has been installed at key locations and is monitored at frequent intervals. A toe berm has been installed to prevent lower slope failure at the creek bed that is located at the slope toe. A finite element stress analysis, which considers the interaction between the soil movement and pipeline, has been generated. This stress analysis evaluated the pipeline stresses due to the slope movements to date, and also due to a possible sudden mass movement. The results are backed up by a bending strain analysis based on inertial in-line inspection data was conducted for several of the lines. This paper presents an overview of the engineering assessment considering structural, material, geotechnical and operational concerns involved in developing an integrity management action plan.

scholarly journals Review on Lateral Stability of Piled Riverine Structures in the Estuaries of Sarawak

2018 ◽  
Vol 7 (3.18) ◽  
pp. 21
Author(s):  
Lee Lin Jye ◽  
Shenbaga R. Kaniraj ◽  
Siti Noor Linda bt Taib ◽  
Fauzan Bin Sahdi
Keyword(s):  
Soft Soil ◽  
Natural State ◽  
Soil Conditions ◽  
Silty Clay ◽  
River Bank ◽  
Soil Movement ◽  
Geotechnical Problem ◽  
Construction Activity ◽  
Lateral Soil Movement ◽  
The Stability

Soft soil conditions with very soft and deep silty clay have constantly endangered the stability of the riverine and estuarine structures in Sarawak. There have been many failures of jetties, wharves and bridges in Sarawak. In many cases of failures, the piles were not designed to resist the lateral movement, unless they were included to stabilize unstable slopes or potential landslides. This practice may be due to reasons such as erroneously judging the river bank as stable in slope stability analysis or simply due to the inexperience of designers. Also, when the river bank approaches the limiting stability in its natural state any construction activity on the river bank could result in lateral soil movement. This paper highlights this important geotechnical problem in Sarawak. Then it presents the details of a few failures of estuarine structures. A review of situations causing lateral loading of piles is then presented. The results of the in-soil and in-pile displacement measurements are shown in this paper and it is found that the computation made to compare between field and 3D modeling is agreeable.  

Heat-Transfer Characteristics of Subsea Pipelines Embedded in Multilayered Soils

SPE Journal ◽  
2020 ◽  
Vol 25 (03) ◽  
pp. 1128-1139
Author(s):  
Dong-Su Park ◽  
Mun-Beom Shin ◽  
Young-Kyo Seo
Keyword(s):  
Heat Transfer ◽  
Analytical Formula ◽  
Soil Conditions ◽  
Burial Depth ◽  
Overall Heat Transfer Coefficient ◽  
Scale Experiment ◽  
Subsea Pipelines ◽  
Multilayered Soils ◽  
Pipeline Design ◽  
Good Agreement

Summary A good pipeline design must ensure that the heat loss is small enough for flow assurance despite unfavorable hydrate and wax depositions. The objective of this study is to experimentally verify a formula for the modified overall-heat-transfer coefficient (OHTC) that considers multilayered soil conditions for steady-state subsea pipelines. A laboratory-scale experiment is conducted to simulate the flows of cold seawater and hot crude oil inside the pipes immersed in multilayered soils at nine burial-depth rates. The obtained results are in good agreement with the data obtained by a previously derived OHTC analytical formula.

Serviceability Assessment of Composite Footbridge Under Human Walking and Running Loads

2015 ◽  
Vol 74 (4) ◽  
Author(s):  
Faraz Sadeghi ◽  
Ahmad Beng Hong Kueh
Keyword(s):  
Concrete Slab ◽  
Model Verification ◽  
Human Walking ◽  
Steel Beams ◽  
Vibration Source ◽  
Design Standards ◽  
Reinforced Concrete Slab ◽  
Codes Of Practice ◽  
Current Design ◽  
Vibration Responses

Footbridge responses under loads induced by human remain amongst the least explored matters, due to various uncertainties in determining the description of the imposed loadings. To address this gap, serviceability of an existing composite footbridge under human walking and running loadings is analyzed dynamically in this paper employing a finite element approach. The composite footbridge is made-up of a reinforced concrete slab simply supported at two ends on top of two T-section steel beams. To model the walking and running loads, a harmonic force function is applied as the vibration source at the center of the bridge. In the model verification, the computed natural frequency of footbridge exhibits a good agreement with that reported in literature. The vibration responses in terms of peak acceleration and displacement are computed, from which they are then compared with the current design standards for assessment. It is found that the maximum accelerations and displacements of composite footbridge in presence of excitations from one person walking and running satisfy the serviceability limitation recommended by the existing codes of practice. In conclusion, the studied footbridge offers sufficient human safety and comfort against vibration under investigated load prescription.

Assessment of Interacting Corrosion Defects in Thin-Walled Pipes

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Ahmed A. Soliman ◽  
Mohammad M. Megahed ◽  
Ch. A. Saleh ◽  
Mostafa Shazly
Keyword(s):  
Nonlinear Finite Element ◽  
Metal Loss ◽  
Test Results ◽  
Defect Depth ◽  
Element Analysis ◽  
Shell Elements ◽  
Codes Of Practice ◽  
Useful Life ◽  
Corrosion Defects ◽  
Interaction Rule

Abstract Corrosion in pipes is usually found in the form of closely spaced defects, which eventually reduce the pipe pressure carrying capacity and piping planned useful life. Codes and standards have been developed to evaluate the effect of such form of metal loss on the piping pressure carrying capacities. However, predictions of such codes are usually conservative, and hence, there is a need to assess their degree of conservatism. The present paper utilizes nonlinear finite element analysis (FEA) in estimating pressure carrying capacities of defective pipes, and hence provides an evaluation of codes degree of conservatism. Shell elements with reduced thickness at the corrosion defect are adopted and their accuracy is assessed by comparison with those of solid elements as well as experimental test results. The influence of defects interaction is investigated by considering two neighboring defects in an inclined direction to each other. The influence of inclination angle, inclined proximity distance between the two defects, and the defect depth to wall thickness ratio are investigated. Comparisons were made with predictions of codes of practice in all cases. Code predictions were found to be conservative compared to FEA results. Furthermore, the interaction rule embedded in the codes for checking for interaction leads to inaccurate predictions for closely spaced defects as it does not include the effect of defect depth.

Influence of Thermal Sweep on Girder Stability during Construction

2018 ◽  
Vol 2672 (41) ◽  
pp. 44-55
Author(s):  
Jeffrey M. Honig ◽  
Zachary S. Harper ◽  
Gary R. Consolazio
Keyword(s):  
Prestressed Concrete ◽  
Precast Concrete ◽  
Solar Heating ◽  
Bridge Girders ◽  
Concrete Bridge ◽  
Design Standards ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Fabrication Tolerances ◽  
Type V

During construction, girder stability of precast, prestressed concrete bridge girders is adversely affected by fabrication imperfections. Consequently, limits on lateral sweep imperfection caused by fabrication tolerances are imposed by design standards, thus reducing the possibility of girder instability and rollover. However, thermal sweep, induced by solar heating during early stages of construction, can add to pre-existing fabrication tolerances thereby amplifying girder imperfections and reducing stability. In the present study, lateral thermal gradients available in the literature were adopted and enhanced for purposes of computing thermal girder sweep. A variety of girder types—PCI BT-63, Florida-I Beams, and AASHTO Type-V—were then investigated to quantify the influence that lateral thermal sweep has on the stability of individual precast concrete bridge girders under lateral wind load. Previously validated finite element analysis modeling and analysis techniques were used to conduct a parametric study that included 10 girder types, varying span lengths, and five geographic locations. Results revealed that thermal sweep may cause wind carrying capacity reductions of the order of 30 to 60% for typical span lengths, and even greater reductions at span lengths that approach maximum design limits. Consequently, it is crucial that thermal sweep, caused by environmental solar-heating conditions, be considered in construction-stage girder stability analyses.

Radial basis function surrogate model-based optimization of guardrail post embedment depth in different soil conditions

2019 ◽  
Vol 234 (2-3) ◽  
pp. 739-761
Author(s):  
Sedat Ozcanan ◽  
Ali Osman Atahan
Keyword(s):  
Finite Element ◽  
Radial Basis Function ◽  
Basis Function ◽  
Computational Cost ◽  
Critical Parameters ◽  
Crash Test ◽  
Soil Conditions ◽  
Embedment Depth ◽  
Element Analysis ◽  
Radial Basis

For guardrail designers, it is essential to achieve a crashworthy and optimal system design. One of the most critical parameters for an optimal road restraint system is the post embedment depth or the post-to-soil interaction. This study aims to assess the optimum post embedment depth values of three different guardrail posts embedded in soil with varying density. Posts were subjected to dynamic impact loads in the field while a detailed finite element study was performed to construct accurate models for the post–soil interaction. It is well-known that experimental tests and simulations are costly and time-consuming. Therefore, to reduce the computational cost of optimization, radial basis function–based metamodeling methodology was employed to create surrogate models that were used to replace the expensive three-dimensional finite element models. In order to establish the radial basis function model, samples were derived using the full factorial design. Afterward, radial basis function–based metamodels were generated from the derived data and objective functions performed using finite element analysis. The accuracy of the metamodels were validated by k-fold cross-validation, then optimized using multi-objective genetic algorithm. After optimum embedment depths were obtained, finite element simulations of the results were compared with full-scale crash test results. In comparison with the actual post embedment depths, optimal post embedment depths provided significant economic advantages without compromising safety and crashworthiness. It is concluded that the optimum post embedment depths provide an economic advantage of up to 17.89%, 36.75%, and 43.09% for C, S, and H types of post, respectively, when compared to actual post embedment depths.

scholarly journals How well does a linear static finite element analysis predict measured strains from a nuclear package tie-down system during rail transportation?

2016 ◽  
Vol 232 (1) ◽  
pp. 222-237 ◽  
Author(s):  
Andrew Cummings ◽  
Glynn Rothwell ◽  
Christian Matthews
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Radioactive Material ◽  
Element Analysis ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Dangerous Goods ◽  
Codes Of Practice ◽  
Low Pass

Freight rail is often the preferred method for transportation of dangerous goods. One particular application is the use of rail to convey radioactive material in purpose-built packages. During transit, packages are secured to a rail wagon bed with a tie-down system. The design of tie-down systems varies considerably depending on the package type and rail vehicle; for example, shackles, turnbuckles, tie rods, gravity wells or transport frames are all commonly used. There are also a large number of different packages in existence that all vary in size and mass, typically 1–7 m in length and 100 kg–100 t in mass. Despite the uniqueness of many transport configurations, the design of tie-down systems is always carried out using a limited set of design load cases as defined in the appropriate Codes of Practice and Standards. Many authors have suggested that the load cases within the standards need revision or question which load cases should apply to which scenario. In a previous experiment, accelerations and strains have been measured on a freight wagon and transport frame of a heavy package during a routine rail journey. From these data, a new insight into the magnitude and nature of loading has been gained. In the present study, the measured accelerations have been used as input to a finite element model of the transport frame, and a method based on correlation between predicted and measured strains has been developed to determine an appropriate low-pass filter cut-off frequency, fc, which separates quasi-static loading from raw dynamic data. The residual dynamic measurements have been assessed using signal processing techniques to understand their significance. The finite element model has also been used to assess the presence of contact and boundary nonlinearities and how they affect the agreement between measured and predicted strains.

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