scholarly journals Investigating the Factors That Reduce the Urban Gas Pipeline Vulnerability to Explosion Threats

2019 ◽  
Author(s):  
Mohammad reza Fallah Ghanbari ◽  
Mohammad Eskandari ◽  
Ali Alidoosti
Keyword(s):  
Soft Soil ◽  
Shell Element ◽  
Friction Angle ◽  
Burial Depth ◽  
Gas Pipelines ◽  
Three Dimensional Model ◽  
Buried Pipelines ◽  
Burial Site ◽  
Pipe System ◽  
Abaqus Software

Introduction: Buried pipelines used to distribute water, gas, oil, and etc. are considered as one of the vital arteries. The experiences of the past wars have confirmed that the invading country focuses on bombing and destroying vital centers, and that gas pipelines can be a source of serious personal and financial losses as an important transmission arteries during war in the event of damage Methods: The vulnerability of buried urban gas pipelines to explosion was determined and the methods for reducing the vulnerability of pipelines were investigated. To this end, the three-dimensional model of the soil-pipe system in ABAQUS software was used to study the effect of factors affecting the pipe behavior, including pipe diameters, diameter to pipe thickness, internal friction angle of soil, soil type, amount of explosives, depth of buried, the distance of explosion site to the pipe burial site, has been investigated on the pipe deformation capacity according to the ALA regulation. The soil was modeled using Solid three elements and shell element. For parametric studies, analyses were performed by the finite element method using ABAQUS software 6.10.1. Results: Studies were conducted for 4 and 12 inch diameter, diameter/thickness ratio of 26, 21 and 35, burial depth of 1, 2, 3 and 4 meters, the explosive charge of 15, 30, 45, 60 and 200 kg TNT and for soil material, hard, soft and clay sands. The results showed that proper burial depth had the most effect in reducing the vulnerability of pipelines against explosive threats. By increasing the pipe thickness and increasing the diameter and applying soft soil around the pipe, a better behavior of the pipe was observed during the explosion Conclusion: To reduce the vulnerability of gas pipelines against explosive threats, the use of buried pipelines has a greater effect on reducing damage due to explosion compared to other parameters, and it is recommended to use this method to increase the resilience of highly important gas pipelines.

Numerical Investigation of Electro-Kinetic Effect on Pipe-Soil Interaction

2017 ◽  
Author(s):  
Hakuri Nwen Joshua ◽  
Fuat Kara
Keyword(s):  
Soft Soil ◽  
Frictional Resistance ◽  
Software Tool ◽  
Kinetic Effect ◽  
Flow Process ◽  
Treated Soil ◽  
Soil Shear Strength ◽  
Electro Osmosis ◽  
Subsea Pipelines ◽  
Abaqus Software

The soft soil content and the high pressure and high temperature (HP/HT) of the operating fliud significantly account for the displacement of subsea pipelines. The abiltiy of the pipeline to resist displacement depents on the soil strength. Increasing the pipe-soil resistance will significantly reduced the pipeline displacement. One method used to increase soil shear strength is the Electro-kinetic (EK) process. This is applied to increase strength of onshore and offshore soil foundations. This paper uses ABAQUS software tool to investigate EK effect on axial displacement of pipeline due to pipe-soil interaction. Studies on both EK treated soil and non-EK treated soil are conducted and compared. Electro-osmosis using the varous flow process is demonstrated and effectively validated. The paper also demontrated the dynamic process due to axial pulling of the pipeline. The resistance developed for both conditions were determined and compared. Due to axial pulling of the pipeline from the soil, the present numerical results shows a remarkable increase of over 100% in frictional resistance to pipeline displacement.

scholarly journals Pressure Settlement Behaviour and Bearing Capacity of Asymmetric Embedded Plus Shaped Footing on Layered Sand

2021 ◽  
Vol 31 (3) ◽  
pp. 152-176
Author(s):  
Priyanka Rawat ◽  
Rakesh Kumar Dutta
Keyword(s):  
Bearing Capacity ◽  
Numerical Study ◽  
Friction Angle ◽  
Thickness Ratio ◽  
Embedment Depth ◽  
Loose Sand ◽  
Dense Sand ◽  
Comparison Of The Results ◽  
Abaqus Software ◽  
Settlement Behaviour

Abstract The aim of the present numerical study was to analyse the pressure settlement behaviour and bearing capacity of asymmetric plus shaped footing resting on loose sand overlying dense sand at varying embedment depth. The numerical investigation was carried out using ABAQUS software. The effect of depth of embedment, friction angle of upper loose and lower dense sand layer and thickness of upper loose sand on the bearing capacity of the asymmetric plus shaped footing was studied in this investigation. Further, the comparison of the results of the bearing capacity was made between the asymmetric and symmetric plus shaped footing. The results reveal that with increase in depth of embedment, the dimensionless bearing capacity of the footings increased. The highest increase in the dimensionless bearing capacity was observed at embedment ratio of 1.5. The increase in the bearing capacity was 12.62 and 11.40 times with respect to the surface footings F1 and F2 corresponding to a thickness ratio of 1.5. The lowest increase in the dimensionless bearing capacity was observed at embedment ratio of 0.1 and the corresponding increase in the bearing capacity was 1.05 and 1.02 times with respect to the surface footing for footings F1 and F2 at a thickness ratio of 1.5.

scholarly journals An Investigation of Effects and Safety of Pipelines due to Twin Tunneling

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Shao Yu ◽  
Riyan Lan ◽  
Junhui Luo ◽  
Zhibo Duan ◽  
Shaokun Ma
Keyword(s):  
Soil Parameters ◽  
Centrifuge Model Test ◽  
Burial Depth ◽  
Buried Pipelines ◽  
Soil Stiffness ◽  
Maximum Settlement ◽  
Dimensionless Analysis ◽  
Bending Strain ◽  
Calculation Results ◽  
Subway Tunnels

To efficiently and accurately predict the effects of twin tunneling on adjacent buried pipelines, the effects of upward and downward relative pipeline-soil interactions were considered. A series of numerical parametric studies encompassing 8640 conditions were performed to investigate the responses of a pipeline to twin tunneling. Based on the dimensionless analysis and normalized calculation results, the concept of equivalent relative pipeline-soil stiffness was proposed. Additionally, expressions for the relative pipeline-soil stiffness and relative pipeline curvature and for the relative pipeline-soil stiffness and relative pipeline settlement were established, along with the related calculation plots. Relying on a comparison of prediction results, centrifuge model test results, and field measured results, the accuracy and reliability of the obtained expressions for predicting the bending strain and settlement of adjacent buried pipelines caused by twin tunneling were validated. Based on the calculation method, the maximum bending strain and maximum settlement of pipelines can be calculated precisely when the pipeline parameters, burial depth, soil parameters, and curve parameters of ground settlement due to tunneling are provided. The proposed expressions can be used not only to predict the maximum bending strain and maximum settlement of pipelines caused by single and twin tunneling but also to evaluate the effects of single and twin tunneling on the safety of existing buried pipelines. The relevant conclusions of this article can also provide a theoretical basis for the normal service of buried pipelines adjacent to subway tunnels.

scholarly journals Interactional Effect of the Influential Parameters on Seismic Behaviour of the Concrete Surface Tanks

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Alirezar Hassanpour Yasaghi ◽  
Mazhar Fatahi ◽  
Seyed Mehdi Seyed Alizadeh
Keyword(s):  
Friction Coefficient ◽  
Modulus Of Elasticity ◽  
Soil Structure ◽  
Friction Angle ◽  
Element Model ◽  
Soil Structure Interaction ◽  
Three Dimensional Model ◽  
Seismic Behaviour ◽  
Structure Interaction ◽  
Soil Modulus

Given to the importance of the tanks and their various applications in different industries, studying the seismic behaviour of these facilities is essential. In such structures, obtaining exact theoretical solution for the seismic behaviour of the tanks is very difficult due to the existence of the soil-structure interaction. In this study, seismic behaviour studying has been taken into account and in addition to considering three-dimensional model of finite element model of a surface rectangular tank and its beneath soil given to SSI and FSI effect, we have done required analysis and Drucker–Prager nonlinear model has been used to investigating more exactly to describe soil behaviour. Euler–Lagrange view with optional mesh displacement has been used for modelling tank-water interaction. According to the obtained results from this modelling, soil beneath the tank and soil-structure interaction affect highly on seismic behaviour of the surface tanks. Meanwhile, the response of the structure to the density changes and soil modulus of elasticity is more sensitive and changes in the coefficient of friction coefficient between the foundation surface and the soil and the internal friction angle do not have tangible effect on the response. The results reveal that the liquid containers response is more sensitive to the changes of the density and the soil modulus of elasticity more than friction coefficient between the surfaces and foundation and internal angle friction.

Theoretical Investigation on the Characteristics of Leak Noise for Natural Gas Pipelines

2020 ◽  
Vol 28 (03) ◽  
pp. 2050005
Author(s):  
Zewei Zhang ◽  
Hongyong Yuan ◽  
Ming Fu ◽  
Tao Chen ◽  
Yan Gao ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Natural Gas ◽  
Dynamic Pressure ◽  
Spectral Characteristics ◽  
Orifice Diameter ◽  
Dipole Source ◽  
Gas Pipelines ◽  
Buried Pipelines ◽  
Spectral Parameters ◽  
Natural Gas Pipelines

This paper is concerned with the spectral characteristics of leak noise at the source relevant to fluid dynamics for natural gas pipelines. Comparison is made between the flow field characteristics for the buried and above-ground pipelines to demonstrate the differences in aero-acoustics generation mechanism. The fundamental spectral parameters including the sound pressure level (SPL) and power spectral density (PSD), are extracted to characterize the leak noise under different pipeline conditions of operation pressure and leak orifice diameter. Numerical results show that the leak noise of buried pipelines has less energy and are more concentrated at lower frequencies, compared with that of above-ground pipelines. It is demonstrated that leak noise is predominantly governed by the dipole and the quadrupole sources, generated from the gas–solid interaction and turbulent disturbance, respectively. It is shown that the dipole source is attenuated and the quadrupole source is amplified with the leak orifice diameter for buried pipelines whereas both are amplified for above-ground pipelines. Moreover, it is suggested that the feature parameters of fluid dynamics, such as the average dynamic pressure and turbulent kinetic energy, can be used to characterize the leak noise mechanism for natural gas pipelines.

Assessment of Trawl Board and Anchor Penetration in Different Soils for Use in Selection of a Burial Depth to Protect Submarine Cables or Pipelines

2009 ◽  
Author(s):  
Se´bastien Resse´guier ◽  
Robert Bendzovski ◽  
Pa˚l Johannes Stro̸m ◽  
Harald Wathne ◽  
Maria Vigsnes ◽  
...  
Keyword(s):  
Soft Soil ◽  
Soft Clay ◽  
Soil Profiles ◽  
Burial Depth ◽  
Fishing Boat ◽  
Efficient Measure ◽  
Submarine Cables ◽  
Selection Of ◽  
Good Agreement ◽  
Different Soils

Burial of submarine pipelines, umbilicals and cables has proven to be an efficient measure for protection against trawling and anchoring. Since the 1980s, extensive burying of both existing and new submarine cables has lead to a considerably decrease in the number of failures and accidents. While in the available standards and recommended practice, no particular guidance can be found related to a safe burial depth in different soils, a number of studies have been carried out showing that a burial depth of 0.6m provides good protection against trawling and fishing activities in most soils. In the meantime, a demand has developed for even deeper burial depth, especially in soft soil in order to protect also against light fishing anchors. A review of the available literature has been carried out in order to determine the possible range of penetration of trawl board in different soils and under different conditions. This showed that the penetration remained limited whatever type of trawl gear or type of soil. In addition, calculations have been performed in order to assess the penetration of trawl boards with different sizes, weights and a range of soil strength. The results show a good agreement with the observed data, confirming that the penetration of trawl gear will be very limited in most clays with exception of very soft clay where excessive penetration can be expected. To assess anchor penetration, a software predicting the behaviour of drag embedment anchors during penetration in clay has been used. The maximum expectable penetration for different anchor sizes and soil profiles has been calculated and are presented in this paper. The results from these calculations also show that for most of the soils, the penetration of an anchor from a light fishing boat will be limited.

scholarly journals Seismic Behaviour of Buried Pipelines: 3D Finite Element Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Smrutirekha Sahoo ◽  
Bappaditya Manna ◽  
K. G. Sharma
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Ground Deformation ◽  
Seismic Wave Propagation ◽  
Pipe Diameter ◽  
Bend Angle ◽  
Burial Depth ◽  
Maximum Magnitude ◽  
Buried Pipelines ◽  
Seismic Behaviour

This paper presents a numerical investigation on six pipeline models to study the seismic response of single and double buried pipelines using finite element method. Different depth and spacing of pipes are considered to investigate their prominent role in the seismic response of buried pipelines under an earthquake loading having PGA of 0.2468 g. In case of single pipeline, the maximum magnitude of final displacement as well as the stress at the end of the seismic sequence is found at the burial depth equal to the pipe diameter. In case of double pipeline, the maximum magnitude of final displacement is found when the spacing between pipes is equal to half the pipe diameter and there is an increasing tendency of developed stress with increase in spacing between pipes. In addition to the above results, the response of the buried pipelines with a particular bend angle (artificially induced bend/buckle) to the permanent ground deformation which is assumed to be the result of seismic wave propagation has also been studied. Remarkable differences in these results are obtained and with these results the designers can reduce seismic risk to their buried pipelines by taking proper precautionary measures.

Analysis and Design of Buried Pipelines for Ice Gouging Hazard: A Probabilistic Approach

2006 ◽  
Vol 129 (3) ◽  
pp. 219-228 ◽  
Author(s):  
Arash Nobahar ◽  
Shawn Kenny ◽  
Tony King ◽  
Richard McKenna ◽  
Ryan Phillips
Keyword(s):  
Probabilistic Approach ◽  
Three Dimensional ◽  
Local Buckling ◽  
Burial Depth ◽  
The Finite Element Method ◽  
Buried Pipelines ◽  
Analysis And Design ◽  
Cold Environments ◽  
Beam Elements ◽  
Environmental Actions

In cold environments, marine pipelines may be at risk from ice keels that gouge the seabed. Large quantities of material are displaced and soil deformations beneath a gouge may be substantial. To meet safety criteria, excessive strains are avoided by burying pipelines to a sufficient depth. In this paper, a probabilistic approach for the analysis and design of buried pipelines is outlined. Environmental actions are applied through distributions of gouge width, gouge depth, subgouge soil deformations, and bearing pressure. Three-dimensional pipe/soil interaction problem is modeled using nonlinear soil springs and special beam elements using the finite element method to estimate pipe response for statistically possible ranges of gouge depths, gouge widths, and burial depths. Relevant failure mechanisms have been considered, including local buckling and a variety of strain and stress based criteria. The methodology presented in the paper was developed and successfully used for several pipeline and electrical cable projects in ice gouge environments. Significantly reduced burial depth requirements have been demonstrated through the application of the probabilistic approach and through the use of strain-based design criteria. Because ice actions are applied through displacements of the soil, more ductile pipes are often necessary to meet reliability targets.

Effects of Crossing Angle on the Behavior of Buried Steel Pipelines Crossing Fault

2013 ◽  
Vol 351-352 ◽  
pp. 630-636
Author(s):  
Nemat Hassani ◽  
Mahdi Shadab Far ◽  
Hadi Kordestani
Keyword(s):  
Parametric Study ◽  
Soil Analysis ◽  
Local Buckling ◽  
Shell Element ◽  
Maximum Strain ◽  
Ground Displacement ◽  
Buried Pipelines ◽  
Steel Pipeline ◽  
Meaningful Relationship ◽  
Pipe Bending

One of the most important factors that may cause a buried steel pipeline to reach the failure limit is the permanent ground displacement. In this paper, assuming SHELL element for pipeline and SOLID element for soil and also considering the interaction of pipe-soil, analysis of buried pipelines crossing fault and parametric study of pipeline behavior were performed. The results of this study show that the behavior of buried pipelines crossing fault is not sensitive to the pipe-fault crossing angle. The main reason for this is the immense strain of the pipe due to the section deformation and local buckling of the pipe body that is caused by the permanent ground displacement. The strain from this phenomenon is so great that the pipe-fault crossing angle cannot have much effect on it. The research also shows that it is better to consider pipe bending than dealing with the pipe-fault crossing angle, because it is a more important parameter in the behavior of buried pipelines crossing faults, and it has a meaningful relationship with the reached maximum strain in the pipeline.

scholarly journals New Dimensionless Correlations for the Evaluation of the Thermal Resistances of a District Heating Twin Pipe System

2021 ◽  
Vol 11 (20) ◽  
pp. 9685
Author(s):  
Massimo Corcione ◽  
Luca Cretara ◽  
Lucia Fontana ◽  
Alessandro Quintino
Keyword(s):  
Thermal Resistance ◽  
Control Volume ◽  
District Heating ◽  
Heat Losses ◽  
Thermal Engineering ◽  
Thermal Conductivity Ratio ◽  
Burial Depth ◽  
Pipe System ◽  
Double Pipe ◽  
Dimensionless Correlations

The heat losses from pre-insulated double-pipe district heating (DH) systems buried in a homogeneous soil are studied numerically. The study is conducted using the diameter of the pipes and their distance, the size of the insulation, the thermal conductivity ratio between the insulation and the soil, as well as the burial depth of the double-pipe system, as controlling parameters. A computational code based on a control-volume formulation of the finite-difference method has been developed using the open-source framework OpenFOAM with the purpose to compute the heat transfer rate across adjacent solid regions with different thermophysical properties. The main scopes of the study are: (a) to investigate in what measure the geometry and the relative position of the warm and cold pipes, as well as the temperature imbalance, the burial depth and the physical properties of both the insulation and the soil, affect the heat losses; (b) to analyze the existence of an optimal configuration of the DH system by the thermal resistance enhancement viewpoint; and (c) to develop accurate correlating equations for the evaluation of the thermal resistance existing between each pipe and its surroundings, useful for practical thermal engineering applications.

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