Nearby Pipelines Research Articles

Research on numerical modeling of ac interference from high-speed railway to nearby buried pipeline

The large-scale construction of high-speed railways and buried pipelines has led to the parallel or intersection of these lines over long distances in some areas, resulting in dynamic AC interference to buried pipelines. In this paper, the modeling method of the AC interference from high-speed railway employing auto-transformer (AT) power supply mode to the buried pipeline was investigated, and the accuracy of the modeling method was verified by the simulation calculation of the actual field case and the comparison with the field data. Through modeling and calculation, the influence of train running position, rail to ground transition resistance and crossing angle on AC interference of high-speed railway is discussed. Based on the above research, it is analyzed that the dynamic AC interference is caused by the change of current distribution and the train load current. The main mechanism of AC interference caused by high-speed railway operation on nearby pipelines is inductive coupling. Especially when the rail to ground transition resistance is less than 50 Ω km, due to the unbalanced distribution of power supply circuit current, the peak AC interference voltage appears on pipeline where the train is located.

Research on Lightning Overvoltage Protection of Line-Adjacent Pipelines Based on Solid-State Decoupling

Existing transmission lines and pipelines are frequently crossed and erected in parallel, meaning that if lightning strikes a wire and causes insulator flashovers, the resulting lightning current will spread through the grounding of the tower where the flashover insulator is located. This dispersion of current can lead to overvoltage effects on nearby pipelines. This study performs simulation calculations to analyze the overvoltage experienced by pipelines due to the dispersion of grounding current from the tower. Furthermore, this paper proposes a method for protecting the pipeline from such an overvoltage. Firstly, the lightning transient calculation model of a transmission line tower is constructed using the electromagnetic transient software ATP-EMTP 5.5. The model calculates the effects of lightning peak currents and soil resistivity on the distribution characteristics of lightning current in the tower, specifically in the area where the flashover insulator is located. Subsequently, a calculation model of the tower grounding grid–natural gas pipeline is developed, taking into account the distribution characteristics of lightning current in the tower. This model analyzes the impact of lightning peak currents, soil resistivity, and pipeline spacing on pipeline overvoltage. Finally, the effectiveness of the solid-state decoupler in mitigating lightning overvoltage in the pipeline is verified. The results demonstrate a positive correlation between the lightning current entering the tower grounding grid through the flashover insulator and the lightning current distribution characteristics. The solid-state decoupling device proves to be effective in reducing the voltage of the pipeline insulation layer, and the simulation results provide the optimal laying length of the bare copper wire.

Effect of DC grounding electrode currents on the corrosion interference behavior of cathodic protection of nearby pipelines

When operating a direct current (DC) transmission grounding electrode in single-pole return ground mode, transient currents traverse the soil, generating stray currents. These currents can intensify the corrosion of long-distance transmission pipelines near the grounding electrode, subsequently altering the pipeline’s cathodic protection potential. Previous investigations into the interference of grounding electrodes on pipeline cathodic protection have overlooked the cathodic protection systems themselves. Addressing this gap, we integrated COMSOL’s electrochemical module with its AC/DC module. To corroborate the accuracy of our COMSOL-based models, we devised specific validation experiments. Additionally, we crafted a COMSOL application builder interface to streamline computations. Consequently, we derived a multi-regression function to express the cathodic protection potential of the pipeline under varied factors and executed a regression tree classification for soil resistivity. To pinpoint optimal corrosion protection for pipelines, we simulated the cathodic protection of segmentally isolated pipelines, determining that potential excursions can be notably mitigated. This research offers insights into both disturbance evaluation and protective strategies for DC transmission and pipelines.

Case study for effects of pile installation on existing offshore facilities in brownfields

New prop structures are meant to be used to strengthen existing ageing offshore platforms in brownfields. This technical note aims to assess the possible effects of pile installation of new prop structures on existing offshore facilities, specifically existing platform piles and nearby pipelines. Based on the case study presented, this work investigates the down-drag and interaction effects of installation-induced vibrations of new piles on the load-displacement response of existing piles, namely pile load-bearing capacity and settlement, as well as assessing vibration levels in the vicinity of existing pipelines.

Centrifuge and numerical modeling of brittle damage of buried pipelines subjected to tunneling induced ground settlements

Tunnel excavations can seriously threaten the structural integrity of nearby pipelines. In the present study, centrifuge tests and numerical simulations are conducted to systematically investigate the brittle damage of buried pipelines subjected to tunneling induced ground settlements. In the numerical model, the pipeline is characterized as peridynamic (PD) shell structures, and the surrounding soil is modeled as discrete independent Winkler springs, and the modified Gaussian distribution profile is incorporated as displacement-controlled boundary conditions on springs. The effectiveness of the proposed numerical model is demonstrated by comparing against the centrifuge test results. A pipeline is subjected to bending due to tunneling until the initiation of cracks, after which the cracks propagate inwardly quickly and penetrate through the cross-section. Eventually, a ring crack occurs at the cross-section above the tunnel centerline. From parametric analyses, the following factors delay the pipeline damage, i.e., thicker pipe wall, shallower burial depth, loosely soils, smaller soil friction angle, and smaller tunnel-pipeline crossing angle. A pipeline with a thicker wall and a higher critical energy release rate can have a greater initial pipe fracture angle. In any case, the fracture angle always increases steadily if the amount of ground settlement continues to grow.

Total AC Interferences Between a Power Line Subject to a Single-Phase Fault and a Nearby Pipeline With Multilayered Soil

This article describes the problem of electromagnetic interferences between power lines and metallic structures, caused by inductive and conductive coupling mechanisms, and the main risks to which personnel and facilities are exposed. An EMTP-based implementation is proposed to predict induced voltage levels on a target circuit, due to interferences caused by overhead power lines under steady-state nominal load, as well as fault conditions, using generalized formulas to represent the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -layered soil. Results are tested by means of a case study of a real shared right-of-way project and comparisons with results obtained using industry-standard software. Results show that the proposed method is accurate, with errors smaller than 8%. Stress voltage values in the interfered pipeline are the order of 50 kV, exposing the structure coating to risk of breakdown, which may lead to corrosion and pipeline failure. A mitigation is designed and proven to reduce voltage values to safe levels, in compliance with the nominal limits from the manufacturer.

Pipeline Availability Limits on the Feasibility of Global Coal-to-Gas Switching in the Power Sector.

Coal-to-gas switching in the power sector, as happening in the U.S., has been a key driver of near-term greenhouse gas emissions reductions. Can this success be replicated around the world? Here, we explore the limits of a global, plant-level, coal-to-gas transition arising from pipeline availability constraints. Globally, only 43% of coal capacity is within 14 km of a nearby pipeline, the median distance for recent coal-to-gas conversions. Furthermore, plant-to-pipeline distance distributions vary widely-only 30% of coal capacity in India is within 14 km of a nearby pipeline. Most global coal fleets are in the intermediate space of balancing two competing interests-having a young coal fleet with high "avoided" emissions potential through coal-to-gas switching but without access to low-cost gas resources. A global stocktake based on coal fleet age, pipeline access, and natural gas supply security suggests that a coal-to-gas transition in the power sector is unlikely to be a universal climate solution.

Experiment and Numerical Simulation on Grouting Reinforcement Parameters of Ultra-Shallow Buried Double-Arch Tunnel

For an ultra-shallow buried double-arch tunnel with a large cross-section, the arching effect is difficult to form in surrounding rock, and grouting method is often adopted to reinforce the surrounding rock. Hence, examining the grouting reinforcement parameters is of great significance for potential failure and collapse prevention. The land part of Haicang undersea tunnel was selected as a case study; laboratory experiments, theoretical analysis, and numerical simulation were performed to determine the grouting solid strength and grouting reinforcement parameters. The effects of different water–cement ratios on slurry fluidity, setting time, bleeding rate, and sample strength were studied by laboratory experiments. A method was proposed to determine the shear strength parameters of grouted surrounding rock through the grout water–cement ratio and the unconfined compressive strength of the rock mass. Numerical simulations were performed for grouting reinforcement layer thickness and the water–cement ratios. The deformation and stability law of tunnel surrounding rock and its influence on surrounding underground pipelines were obtained considering the spatial effect of tunnel excavation and grouting reinforcement. The reasonable selection range of grouting reinforcement parameters was proposed. The initial setting time and bleeding rate of cement slurry increased with the increasing water–cement ratio, while the viscosity of cement slurry and sample strength decreased with the increasing water–cement ratio. The shear strength parameters of grouted surrounding rock were determined by the water–cement ratio of grout and unconfined compressive strength of rock mass before grouting. When the thickness of grouting reinforcement layer h = 1.5 m and the water–cement ratio of grout was suggested η = 0.85, the surface settlement, the deformation of the vault, and the deformation of the nearby pipeline all met the design. Moreover, the construction requirements were more economical. Research results can provide a reference for the selection of grouting reinforcement parameters for similar projects.

Numerical Analysis of the energy loss mechanism in cavitation flow of a control valve

Cavitation can cause considerable damage within control valves and nearby pipelines. Despite the extensive research, the mechanism of energy loss in cavitation flow of control valves is not yet adequately understood. In this study, the mechanism of mechanical energy transfer and loss in unsteady cavitation flow and the effect of cavitation on energy loss of a control valve with different pressure ratio conditions were numerically investigated by the validated numerical method based on the LES model. A dimensionless parameter called flow energy gradient was proposed to evaluate the rate of energy loss. Results show that the contribution of the energy loss is much greater in the region of valve seat throat where strong throttling and severe cavitation occur. The total energy loss in the control valve is composed by the throttling loss and the additional energy loss of cavitation, the latter leads to an increase in flow resistance and a decrease in flow capacity of the control valve. Moreover, the additional energy loss induced by cavitation increases with the severity of cavitation, which may result from the change of the liquid-vapor phase.

A multi-time scale vibration surveillance system for third-party threats on urban pipeline

Third-party interference caused by construction activities have seriously jeopardized the security of underground pipelines. Following the process of signal collection—feature extraction and selection—multi-time scale identifying— combining results by voting, this paper proposes a multi-time scale surveillance system for interference prevention of thirdparty threats on the nearby pipeline by using ground vibration monitors. The system focuses on the two major urban construction activities induced by excavator breaking hammers and road cutters, and presents excellent performance under the noise of traffic and pedestrian. Three features including the short-time zero-crossing rate, subset differential parameter and the Mel frequency cepstrum coefficients are selected by the analysis of the maximal information coefficient and feature importance for identifying the patterns of different third-party activities. The crucial part of the surveillance system consists of the two random forest-based classifiers trained by 0.5 s samples and 8 s samples respectively, and the alarm depends on the voting of the two classifiers, which brings the perspectives on different time scales for decision making. In the test, 96.14% of the threat vibration signals can be detected, while only 0.45% of the environmental noise signals cause false alarms.

An investigation of harmonic induced voltages on medium-voltage cable sheaths and nearby pipelines

This paper investigates the impact of harmonics in underground medium-voltage cables to the induced voltages on the cable sheaths of the excited system as well as the corresponding electromagnetic interference (EMI) to nearby coated pipelines. To evaluate systematically the harmonic induced voltages on both cable sheaths and pipelines a benchmarking analysis is carried out. The accuracy of different simulation models is also investigated. The feasibility and practical application of this paper is examined in a cable system excited by current harmonics using data obtained from measurements of the recent literature.

Probabilistic Mixture Model for Mapping the Underground Pipes

Buried pipes beneath our city are blood vessels that feed human civilization through the supply of water, gas, electricity, and so on, and mapping the buried pipes has long been addressed as an issue. In this article, a suitable coordinate of the detected area is established, the noisy Ground Penetrating Radar (GPR) and Global Positioning System (GPS) data are analyzed and normalized, and the pipeline is described mathematically. Based on these, the Probabilistic Mixture Model is proposed to map the buried pipes, which takes discrete noisy GPR and GPS data as the input and the accurate pipe locations and directions as the output. The proposed model consists of the Preprocessing, the Pipe Fitting algorithm, the Classification Fitting Expectation Maximization (CFEM) algorithm, and the Angle-limited Hough (Al-Hough) transform. The direction information of the detecting point is added into the measuring of the distance from the point to nearby pipelines, to handle some areas where the pipes are intersected or difficult to classify. The Expectation Maximization (EM) algorithm is upgraded to CFEM algorithm that is able to classify detecting points into different classes, and connect and fit multiple points in each class to get accurate pipeline locations and directions, and the Al-Hough transform provides reliable initializations for CFEM, to some extent, ensuring the convergence of the proposed model. The experimental results on the simulated and real-world datasets demonstrate the effectiveness of the proposed model.

Impact of pile foundations adjacent to tunnels in sandy stratum

In recent years, with rapid urbanization and construction of underground pipeline facilities for the transmission of electricity, supply of water, sewage disposal or provision of facilities like telephone lines, gas pipe lines, etc., it is highly probable to encounter an existing pipeline system in the vicinity of a proposed foundation of a structure. Hence, design and construction of new foundation structure near the existing subsurface pipeline system is imperative and should be addressed for keeping either a minimum safe clearance between tunnel/buried pipe and pile without compromising the capacity of pile or estimating the reduced capacity due to existing nearby pipeline or tunnel, which is an important aspect in the analysis and design of pile foundation. Present study demonstrates a model and numerical study of the behaviour of a single pile in the vicinity of existing tunnel/buried pipe in a cohesionless soil. During experimental work, a small scale pile model was tested for its load–settlement behaviour without and with the existence of buried PVC pipe modelled as a tunnel in the vicinity near the shaft. The complete experimental set-up consisted of a steel box filled with sand at two different relative density values and vertical concentric load was applied on the model pile through a hydraulic jack and reaction frame arrangement connected with a proving ring. Results of pile loading test have been provided, which demonstrate the tunnel–pile interaction problem effect on the pile capacity, and it was also numerically verified using commercially available finite-element tool. With due verification, parametric study is performed, through finite-element analysis, by varying the range of input parameters such as unit weight, internal friction angle, diameter of pile and elastic modulus of pile material to the soil modulus ratio. Based on the results of numerical analysis in terms of load–settlement curves, it is noted that there is 15–20% reduction in the pile capacity of a single pile to be installed in cohesionless soil in the vicinity of the existing buried pipe or tunnel, which depends on the geometries of the pile and tunnel construction, properties of the in situ soil and zones of influence due to relative stiffness of soil and pipe materials.

Safety Monitoring of Buried Pipeline with Socket Joints Subjected to Ground Deformation Using MEMS Inclinometers

Ground deformation, which is a common consequence of surface loads, construction activities, excavation work, subterranean cavitation, soil subsidence, and so on, poses a serious threat to nearby pipelines. This work proposes a structural health monitoring (SHM) system to evaluate the safety of buried pipelines with socket joints subjected to ground deformation. Using the developed wireless microelectromechanical system (MEMS)-based inclination sensors, this system has many advantages over the traditional leveling method, including real-time monitoring, high precision, low power consumption, and economic and labor efficiency. Field tests of a 12-m buried pipe with three socket joints were carried out to observe the pipe responses under surface loading. A simplified model for finite-element (FE) analysis was then proposed to simulate the mechanical behavior of the socket joint under axial force and bending moment, which has been verified to be effective to represent the rotation responses of the joint. Using this model, numerical case studies were conducted of the buried pipeline subjected to uneven ground deformation in the general form, based on which a safety monitoring strategy was presented to achieve the three targets of detection, localization of the interference, and evaluation of its effect on pipelines.

Estimating the Effects of Tunnelling on Preexisting Jointed Pipelines

Tunnel excavation inevitably results in ground movements and changes in soil stress, leading to additional stress on and settlement of nearby buried pipelines. This article focuses on the response of jointed pipelines to twin tunnelling. The relationship between the relative pipe‐soil displacement and the relative pipe‐soil stiffness was first determined. Based on this analysis, a series of numerical parametric studies encompassing 7776 conditions were performed to investigate the responses of a jointed pipeline to twin tunnelling. The results are used to estimate a regression equation for the relationship between the relative pipe‐soil stiffness and the normalized maximum joint rotation angle. This equation can be used for the direct calculation of the maximum joint rotation angle that will result from single or twin tunnelling and for the assessment of the tunnelling‐induced risk to jointed pipelines. The applicability and reliability of the regression equation are validated by comparing the calculated values with the results of earlier centrifuge tests.

A unified Lagrangian formulation for solid and fluid dynamics and its possibility for modelling submarine landslides and their consequences

Consequences of submarine landslides include both their direct impact on offshore infrastructure, such as subsea electric cables and gas/oil pipelines, and their indirect impact via the generated tsunami. The simulation of submarine landslides and their consequences has been a long-standing challenge majorly due to the strong coupling among sliding sediments, seawater and infrastructure as well as the induced extreme material deformation during the complete process. In this paper, we propose a unified finite element formulation for solid and fluid dynamics based on a generalised Hellinger–Reissner variational principle so that the coupling of fluid and solid can be achieved naturally in a monolithic fashion. In order to tackle extreme deformation problems, the resulting formulation is implemented within the framework of the particle finite element method. The correctness and robustness of the proposed unified formulation for single-phase problems (e.g. fluid dynamics problems involving Newtonian/Non-Newtonian flows and solid dynamics problems) as well as for multi-phase problems (e.g. two-phase flows) are verified against benchmarks. Comparisons are carried out against numerical and analytical solutions or experimental data that are available in the literature. Last but not least, the possibility of the proposed approach for modelling submarine landslides and their consequences is demonstrated via a numerical experiment of an underwater slope stability problem. It is shown that the failure and post-failure processes of the underwater slope can be predicted in a single simulation with its direct threat to a nearby pipeline and indirect threat by generating tsunami being estimated as well.

E&amp;P Notes (March 2018)

E&amp;P Notes (March 2018)

Assessment of d.c. traction stray currents effects on nearby pipelines

Purpose – dc electrified traction systems are a potential source of stray currents. The purpose of this paper is to evaluate the harmful effects (electrolytic corrosion) that an electrified railway has on nearby earth return circuits (e.g. pipelines). Design/methodology/approach – The electric circuit approach, based on the earth return circuit theory, to model stray currents interference on extended structures is presented. An exact method of calculation is applicable to any dc railway system in which tracks can be represented by a single earth-return circuit (equivalent rail) with current energization. In the approximate method, the equivalent rail with current energization is modeled as a large multinode electrical equivalent circuit with lumped parameters. The circuit is a chain of basic circuits, which are equivalents of homogenous sections of the rail. The electrode kinetics (polarization phenomenon) is taken into account in the model developed. Findings – Formulas in partially closed forms are derived applicable to the analysis of currents and potentials along a pipeline laid in the proximity with railway tracks. The attempt is undertaken, to incorporate the electrode kinetics into the simulation model in which the polarization phenomenon (Tafel equation) is modeled by a non-linear voltage source with source voltage being iteratively calculated. The polarization potential along the affected pipeline can be determined. Originality/value – The pipeline electrochemical response (polarization behavior – non-linear phenomenon on the interface metal-soil electrolyte) to the dc stray currents interference is innovative incorporated into the simulation model with lumped parameters using the iterative process.

Three-Dimensional Centrifuge Modeling of Ground and Pipeline Response to Tunnel Excavation

AbstractTunnel excavation inevitably induces stress changes in the surrounding soil leading to significant ground movements and additional stress in nearby pipelines. Most previous studies simplified tunnel–pipe interaction as a plane strain problem and focused on the case in which the pipeline intersects the tunnel perpendicularly. In this study, centrifuge tests were conducted to investigate the three-dimensional response of the ground and pipeline to tunneling, considering different pipeline orientations with respect to the tunneling direction. When the tunnel face was located within ±1.25D (tunnel diameter) away from the monitoring section, the ground settlement and pipe strain induced were more than 95% of the maximum recorded. When the pipeline intersected the tunnel perpendicularly, the maximum pipe strain always occurred above the tunnel centerline. However, when the pipeline intersected the tunnel at an angle of 60°, the location of maximum pipe strain shifted as the tunnel advanced. The maximum ...

Transient analysis of inductive induced voltage between power line and nearby pipeline

Among the available literature on electromagnetic interference between high voltage power lines and nearby pipelines, the topic of transient induced voltage on the pipelines are rarely discussed. Fault in high voltage transmission systems is usually cleared in several cycles, sometimes even before the fault current reaches the steady state. This paper proposes an analytical approach for calculating the transient induced voltage and current on a pipeline due to inductive coupling using a circuit model. A numerical example is studied to demonstrate the waveforms of transient induced voltage and current on the pipeline. Simulation results show that the transient peak of the induced voltage is greater than steady state values. Therefore, it is necessary to study the induced voltage and current during the transient period.