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Damage to buried pipes under seismic landslide actions has been reported in many post-earthquake reconnaissance. The landslide-pipe problem in the technical literature has been often investigated using simplified analytical methods. However, the analytical methods ignore the real mechanism of pipe response under natural dynamic slope instability. The dynamic slope instability is significantly influenced by its lateral boundary interface (LBI) characteristics. In this study, slope-pipe interaction (SPI) under seismic loading, focusing on the effect of LBI properties, is evaluated by continuum numerical simulation using the SANISAND constitutive model in FLAC3D. The results show that the geometry of the failure mass varies from 2D to 3D by increasing the stiffness at the slope boundaries (from smooth to hard) and the maximum pipe deformation decreases by around 40%. Moreover, the response components of maximum axial stress, bending moment, and shear stress of the pipe occur at the end sections of the buried pipe and near the boundaries of the landslide zone. However, the maximum pipe deflection occurs in the middle section of the pipe. The results of shear force-shear displacement curves demonstrate that the soil-pipe interaction stiffness is variable along the pipe length and can be estimated by a hyperbolic equation. [ABSTRACT FROM AUTHOR]

Microbiologically influenced corrosion (MIC) caused by sulfate‐reducing bacteria (SRB) is a major threat to buried pipelines. The crevices beneath disbonded coatings provide the environment for the survival and growth of SRB, accelerating the attachment of SRB and significantly reducing the effectiveness of buried pipelines. In this work, the influence of initial pH values (6.4, 8.0) and SRB concentrations (2.0 × 101, 4.5 × 102, 2.5 × 103 cells/mL) were investigated on the behaviors of L415 carbon steel. The results indicated that the overall uniform corrosion rate of L415 carbon steel decreased while the maximum pitting corrosion rate exhibited an increasing trend with the increasing of initial concentration of SRB. In comparison to the pH 6.4 environment, the overall risk of pitting corrosion in pH 8.0 environment was reduced due to the biomineralization of SRB, enhancing the protection of metal materials. [ABSTRACT FROM AUTHOR]

Buried pipelines subjected to permanent ground deformations (through, e.g., earthquake-induced liquefaction or fault rupture) often experience widespread damage. Regardless of the direction of ground movement, pipelines tend to respond and experience damage axially due to their directional stiffness characteristics. In addition, case studies and previous testing have shown that damage is concentrated at the pipe joints due to their lower strength compared with a pipe barrel. Previous testing has also shown that axial forces increase significantly when pipe connections have jointing mechanisms, such as coupling restraints, with larger diameters than the pipe barrel alone. These enlarged joints act as anchors along the pipe, increasing the soil resistance at these locations. Current methods for predicting the axial force along a pipe underpredict the force demands and oversimplify the mechanics of soil resistance on the joint face. This study conducts a series of 12 pipe-pull tests in a centrifuge, varying joint diameter and burial depth, to quantify the axial forces developed. A strong linear correlation was observed between the soil resistance on a joint face and the joint surface area and burial depth. The study also proposes an analytical solution based on pullout capacity design equations for vertical anchor plates as a function of soil and pipe joint properties. The proposed solution to calculate joint resistance is in good agreement with the centrifuge tests performed for this study and previous full- and model-scale experiments. The proposed prediction equation is anticipated to have future applications to other buried structures because it is based on mechanisms of passive resistance commonly encountered in underground structures and lifelines. [ABSTRACT FROM AUTHOR]

The importance of the buried pipelines lies in two main topics: the first is related to the very long length of these pipes, and therefore protecting them is expensive. The second topic is related to environmental pollution due to leaching, which is considered one of the main pollutants of groundwater. The research reviews the effects of geosynthetic reinforcement and its effect on buried pipelines subjected to different loading conditions to reduce the stresses on them and thus prevent leakage. The loads covered in this literature are the following: static load, dynamic load, permanent ground deformation, accidental damage, uplift pressure, explosion, lateral loading, and abrasive shear loading. The research focused on the use of synthetic ground reinforcements to protect these pipes. Available experimental and numerical investigations indicate the potential of using geosynthetics to reduce the effects of external loads on buried pipelines. The investigated studies proved that the protection of buried pipes with different types of geosynthetics is a successful method and decreased the stresses transformed to buried pipes. Most of the studies (45%) dealt with buried pipes subjected to static loading. The conventional geosynthetic material used in the protection of buried pipes is geogrid (38%). [ABSTRACT FROM AUTHOR]

When traversing through an active strike-slip fault, buried pipelines may be subjected to permanent ground deformation (PGD), causing large strains in the pipeline during an earthquake. The presence of bends near the fault-crossing zones may further increase the strain in the pipe. Moreover, it is well acknowledged that bends are the most vulnerable location to earthquake damage, mainly when compressive strain develops due to PGD. Hence, most design guidelines recommend constructing pipelines without field bends, elbows, and flanges crossing the fault zone. However, it is not always possible to provide only a straight segment of the pipeline, especially for blind faults where the location of the faults is unknown. Hence, the present study aims to investigate the response of buried continuous steel pipelines with field bends subjected to strike-slip faulting by conducting an extensive parametric study. A three-dimensional pipe-soil interaction model is developed in a finite element framework for this study. The pipeline response in terms of its maximum von-Mises stress and maximum longitudinal stress and strain due to fault crossing is studied for various influencing parameters such as pipe bend angle, soil strength, pipe burial depth, and distance of the fault trace from the bend. Based on the results obtained, suitable relationships in terms of modification factors over the response of a straight pipeline as a function of a few critical parameters are determined using regression analyses. It is concluded that providing bends to the pipeline can significantly affect its structural response when subjected to fault displacement when the fault trace is close to the pipe bend. The primary outcome of this investigation would be to suggest a simplified methodology to estimate the response of pipelines having field bends while crossing fault lines from the response of straight pipelines in a similar scenario. [ABSTRACT FROM AUTHOR]

AbstractThis study proposes an efficient and effective method to estimate the water temperature inside buried gas pipelines during hydrostatic tests. The goal is to develop appropriate correlations that can easily calculate the pipeline’s water temperature, taking into account the adjacent soil temperature variations, pipeline size, thickness, and coating properties. The study first presents a mathematical model of the problem, introducing relevant non-dimensional parameters. Then, the unsteady problem is numerically analyzed, considering all significant variables, and next, the effects of each non-dimensional parameter on the water temperature are carefully examined and evaluated. The numerical simulations show that the difference between the pipeline water temperature and the adjacent soil temperature can be up to 80%, particularly for large-diameter pipelines. The proposed correlations are able to estimate the pipeline water temperature during the hydrostatic test with around 1% deviation from the direct numerical solutions. Additionally, the results indicate that for typical test cases, the pipeline size is the main influential parameter, while the pipeline thickness and material coating with conventional properties do not significantly affect the water temperature variations. [ABSTRACT FROM AUTHOR]

External corrosion poses a significant threat to the integrity and lifespan of buried pipelines. Accurate prediction of corrosion rates is important for the safe and efficient transportation of oil and natural gas. However, limited data availability often impacts the performance of conventional predictive models. This study proposes a novel composite modeling approach integrating kernel principal component analysis (KPCA), particle swarm optimization (PSO), and extreme learning machine (ELM). The key innovation lies in using KPCA for reducing the dimensionality of complex input data combined with PSO for optimizing the parameters of the ELM network. The model was rigorously trained on 12 different datasets and comprehensively evaluated using metrics such as the coefficient of determination (R2), standard deviation (SD), mean relative error (MRE), and root mean square error (RMSE). The results show that KPCA effectively extracted four primary components, accounting for 91.33% of the data variability. The KPCA-PSO-ELM composite model outperformed independent models with a higher accuracy, achieving an R2 of 99.59% and an RMSE of only 0.0029%. The model comprehensively considered various indicators under the conditions of limited data. The model significantly improved the prediction accuracy and provides a guarantee for the safety of oil and gas transport. [ABSTRACT FROM AUTHOR]

Overtime, continuous research efforts have been devoted to investigating the effects of permanent ground deformation (PGD) on buried pipelines. These efforts have faced major uncertainties in the ground movement patterns that impose displacement-controlled loads on pipelines. This study presents a systematic review of the PGD patterns available in the literature for the analysis of buried pipelines, with particular emphasis on the PGD directions relative to pipeline axes. Depending on the directions, PGD patterns are divided into three groups: longitudinal, transverse and oblique. The relevant literature is organized into four main categories: experimental, numerical, analytical and probabilistic. Seven different PGD patterns (block, ramp, step, ridge, sinusoidal, asymmetric ridge, and asymmetric sinusoidal) available in the literature are discussed in this study. All these PGD patterns, except asymmetric sinusoidal, were applied in the longitudinal direction. In contrast, only three (block, sinusoidal and asymmetric sinusoidal) were applied transversely, which indicates a potential gap considering the randomness of PGD relative to pipeline axes. Besides, one additional PGD pattern (trapezoidal) is suggested in the present study based on the literature review. The findings of the present study show that 84 % of the reviewed cases considered either block or sinusoidal PGD pattern, while only 16 % considered the other PGD patterns (ramp, step, ridge, asymmetric ridge, and asymmetric sinusoidal). Almost all these 16 % reviewed cases assumed pipelines primarily as linear elastic materials. Based on these observations, the present study recommends a comprehensive study on the effects of all the mentioned PGD patterns on pipelines in all three directions. [ABSTRACT FROM AUTHOR]

The failure of buried pipelines can lead to serious consequences such as explosions, environmental pollution, settlement, as well as economic loss. To prevent these outcomes, it is crucial to identify the causes of failure and monitor their signs. One of the main causes of failure is unexpected third-party interference (TPI), which is particularly challenging to detect. Regarding to this issue, this study proposes a new algorithm for monitoring impact damage, which can be used for prompt response and damage prevention. The algorithm is integrated into the system using two approaches. The first approach focuses on detecting the location of the damage (referred to as source location). A kurtosis-based transfer function was newly proposed to selecting the optimal frequency band for time-difference-of-arrival based source location, resulting in accurate pinpointing of damage, even in a noisy environment. The second approach is used to determine whether impact damage has actually occurred by observing newly suggested features in both the time and frequency domains (referred to as anomaly detection). These features evaluate the presence of damage and the similarity between signals. As a result, it was evaluated that the field applicability was higher than that of conventional methods, and the superiority of the proposed method was also verified through field experiments. The method proposed in this study is expected to enable immediate response when the integrity of the buried pipelines is on the line of failure due to TPI. [ABSTRACT FROM AUTHOR]

Buried pipelines are susceptible to non-uniform excitations in different directions, which may lead to severe damage. This study investigates the pipeline performance under longitudinal and transverse non-uniform excitations via multi-point shaking table tests. The results demonstrated that the seismic response of pipeline was affected more by soil inconsistent motion under transverse non-uniform excitations, while it was affected more by the degree of pipeline–soil interaction in longitudinal direction. The pipeline maximum peak bending strains were larger than the maximum peak axial strains at higher loading intensity. These indicated that the pipeline response mechanisms are different under longitudinal and transverse non-uniform excitations. [ABSTRACT FROM AUTHOR]

Currently, mixing hydrogen into natural gas networks is the most cost-effective method for transporting significant quantities of hydrogen over long distances. However, after mixing natural gas with hydrogen, the properties of the mixed gas will change significantly, manifested as faster diffusion rate, increased combustion rate, and wider flammability limit. In this paper, a CFD numerical simulation method is used to establish a numerical model for the leakage and diffusion of buried hydrogen-blended natural gas (HBNG) pipelines, and the concentration diffusion trend and velocity flow field distribution of HBNG in soil under different leakage conditions are studied, as well as the alarm time when HBNG diffusion reaches the lower flammability limit (LFL) at the ground surface. At the same time, the effects of hydrogen blending ratio (HBR), pipeline operating pressure, soil porosity and leakage diameter on HBNG leakage and diffusion are investigated. The simulation results indicate that increasing the HBR will increase the diffusion rate of the mixed gas and reduce the LFL, resulting in a decrease of the alarm time. The increase of pipeline operating pressure and leakage diameter will increase the mass flow rate, and the increase of soil porosity will reduce the resistance when HBNG spreads in the soil. All three cases will significantly reduce the alarm time. The results of this study will provide some references for the emergency response work of buried pipeline leakage and the risk assessment of HBNG leakage and explosion. • A numerical model of leakage and diffusion in a buried hydrogen-blended natural gas pipeline is established. • The concentration diffusion trend of hydrogen-blended natural gas in soil under different leakage conditions are studied. • The effects of hydrogen blending ratio, pipeline operating pressure, soil porosity and leakage hole diameter on HBNG leakage and diffusion are investigated. [ABSTRACT FROM AUTHOR]

Fault movement during earthquakes is a geotechnical phenomenon threatening buried pipelines and with the potential to cause severe damage to critical infrastructures. Therefore, effective prediction of pipe displacement is crucial for preventive management strategies. This study aims to develop a fast, hybrid model for predicting vertical displacement of pipe networks when they experience faulting. In this study, the complex behavior of soil and a buried pipeline system subjected to a normal fault is analyzed by using an artificial neural network (ANN) to generate predictions the behavior of the soil when different parameters of it are changed. For this purpose, a finite element model is developed for a pipeline subjected to normal fault displacements. The data bank used for training the ANN includes all the critical soil parameters (cohesion, internal friction angle, Young's modulus, and faulting). Furthermore, a mathematical formula is presented, based on biases and weights of the ANN model. Experimental results show that the maximum error of the presented formula is 2.03%, which makes the proposed technique efficiently predict the vertical displacement of buried pipelines and hence, helps to optimize the upcoming pipeline projects. [ABSTRACT FROM AUTHOR]

Overtime, continuous research efforts have been devoted to investigating the effects of permanent ground deformation (PGD) on buried pipelines. These efforts have faced major uncertainties in the ground movement patterns that impose displacement-controlled loads on pipelines. This study presents a systematic review of the PGD patterns available in the literature for the analysis of buried pipelines, with particular emphasis on the PGD directions relative to pipeline axes. Depending on the directions, PGD patterns are divided into three groups: longitudinal, transverse and oblique. The relevant literature is organized into four main categories: experimental, numerical, analytical and probabilistic. Seven different PGD patterns (block, ramp, step, ridge, sinusoidal, asymmetric ridge, and asymmetric sinusoidal) available in the literature are discussed in this study. All these PGD patterns, except asymmetric sinusoidal, were applied in the longitudinal direction. In contrast, only three (block, sinusoidal and asymmetric sinusoidal) were applied transversely, which indicates a potential gap considering the randomness of PGD relative to pipeline axes. Besides, one additional PGD pattern (trapezoidal) is suggested in the present study based on the literature review. The findings of the present study show that 84 % of the reviewed cases considered either block or sinusoidal PGD pattern, while only 16 % considered the other PGD patterns (ramp, step, ridge, asymmetric ridge, and asymmetric sinusoidal). Almost all these 16 % reviewed cases assumed pipelines primarily as linear elastic materials. Based on these observations, the present study recommends a comprehensive study on the effects of all the mentioned PGD patterns on pipelines in all three directions.

The seismic response of buried pipeline is significantly affected by the soil around the pipeline. In this study, a numerical analysis model of the pipeline and the soil around the pipeline is built, and the finite element numerical analysis of its seismic response law is conducted to address the problem of pipeline soil seismic coupling response. A shaking table test of the seismic response of buried pipeline under two-way seismic excitation is performed based on the developed two-way layered shear continuum model soil box. The peak strain response at the middle section of the pipeline grows fastest, the peak strain of the pipeline under non-uniform seismic excitation constantly exceeds that under uniform excitation, and the axial strain of the pipeline exhibits more sensitivity to earthquake than the bending strain, as indicated by the results of numerical analysis and shaking table test. The peak value of soil acceleration response under non-uniform excitation exceeds under uniform excitation. The displacement of soil increases with the height. The pipeline soil interaction becomes more intense under non-uniform excitation, and the relative movement between pipeline and soil becomes more significant. The seismic excitation more significantly affects the axial displacement of soil. The peak value of soil acceleration response varies from larger along the pipeline to larger along the axis with the increase of the loading grade. A slight difference exists between the peak value of axial and transverse acceleration response of the pipeline. The peak value of pipeline acceleration response declines in the axial direction than the peak value of soil acceleration response, whereas it rises in the transverse direction than the peak value of soil acceleration response, especially under non-uniform excitation. As revealed by the above results, the effect of bidirectional non-uniform seismic excitation on the lateral pipeline soil interaction is enhanced, and soil is more seriously damaged. [ABSTRACT FROM AUTHOR]

Buried flexible pipes are allowed to deflect up to 2–5% of the pipe diameter, which can become problematic for the connected direct-bury, large-diameter butterfly valves. The complex behavior of the pipe–valve–soil system makes it difficult to predict the deflection of the pipe/valve system. In the absence of field/experimental studies, the application of finite element analysis (FEA) seems necessary to predict deflection and stresses and to avoid potential downtime associated with disruption of service. This paper described the FEA of a large-diameter pipe–valve system, with different backfills under gravity, overburden, and internal pressure loads. The effects of modeling different components of the system (e.g., flanges, bearing housing, gate disc, etc.) were described and investigated. The goal of this study was to provide insight into the design and installation of direct-bury pipe–valve systems and evaluate current installation methods in the absence of guidelines. In addition, the level of modeling details required for FEA to yield accurate results was discussed. [ABSTRACT FROM AUTHOR]

Buried flexible pipes are allowed to deflect up to 2–5% of the pipe diameter, which can become problematic for the connected direct-bury, large-diameter butterfly valves. The complex behavior of the pipe–valve–soil system makes it difficult to predict the deflection of the pipe/valve system. In the absence of field/experimental studies, the application of finite element analysis (FEA) seems necessary to predict deflection and stresses and to avoid potential downtime associated with disruption of service. This paper described the FEA of a large-diameter pipe–valve system, with different backfills under gravity, overburden, and internal pressure loads. The effects of modeling different components of the system (e.g., flanges, bearing housing, gate disc, etc.) were described and investigated. The goal of this study was to provide insight into the design and installation of direct-bury pipe–valve systems and evaluate current installation methods in the absence of guidelines. In addition, the level of modeling details required for FEA to yield accurate results was discussed.

External corrosion poses a significant threat to the integrity and lifespan of buried pipelines. Accurate prediction of corrosion rates is important for the safe and efficient transportation of oil and natural gas. However, limited data availability often impacts the performance of conventional predictive models. This study proposes a novel composite modeling approach integrating kernel principal component analysis (KPCA), particle swarm optimization (PSO), and extreme learning machine (ELM). The key innovation lies in using KPCA for reducing the dimensionality of complex input data combined with PSO for optimizing the parameters of the ELM network. The model was rigorously trained on 12 different datasets and comprehensively evaluated using metrics such as the coefficient of determination (R2), standard deviation (SD), mean relative error (MRE), and root mean square error (RMSE). The results show that KPCA effectively extracted four primary components, accounting for 91.33% of the data variability. The KPCA-PSO-ELM composite model outperformed independent models with a higher accuracy, achieving an R2 of 99.59% and an RMSE of only 0.0029%. The model comprehensively considered various indicators under the conditions of limited data. The model significantly improved the prediction accuracy and provides a guarantee for the safety of oil and gas transport.

In order to better understand the research status in the field of HVDC interference in buried pipelines by numerical simulation technology, the research results of HVDC interference in buried pipelines at home and abroad were summarized. The method of calculation of numerical simulation technology was introduced, the calculation principles of two numerical simulation and calculation softwares, CDEGS and Beasy, were analyzed, and their advantages and disadvantages were compared. In addition, the application status of numerical simulation technology in the study of HVDC interference in buried pipelines was summarized. On this basic, the current problems in numerical simulation technology were pointed out, and the future calculation direction of numerical simulation technique used for HVDC interference in buried pipelines was prospected, which would provide reference and inspiration for relevant researchers and engineers.

Dynamic loads generated by heavy vehicles are among the loads resisted by pipelines buried under road surfaces. Most recent analyses are based on static assumptions; however, in practice, vehicle loads change dynamically. In this study, the finite element model of the pipe–soil interaction of a buried pipeline was established using the ABAQUS 2020 finite element software, and dynamic loads were applied above the model soil to simulate the influence of vehicles above the highway on the buried X80 pipeline. The mechanical responses of different influencing factors to buried pipelines were analyzed. Increasing the pipe diameter and burial depth decreases the effect of vehicle rolling on the buried pipeline. The mass of the vehicle is the most significant factor that influences the stress and strain on the pipeline. The stress increase of the conventional vehicle load on the X80 gas pipeline does not exceed 10 MPa, and the maximum shape variable of the pipeline is within 13 mm. This study provides a data reference and a risk warning regarding the rolling of buried natural gas pipelines under a single vehicle load. [ABSTRACT FROM AUTHOR]

Currently, accelerated aging tests are widely used to study the aging process of polyethylene pipelines. However, this approach can only simulate one or several main influencing factors in the natural environment, which are often quite different from the actual environment of the buried pipelines. In this study, five types of PE80 buried pipelines in service for 9e18 years were taken as the research object, while new PE80 pipelines were taken as the reference group. The aging process and mechanism of polyethylene buried pipelines were studied through mechanical and chemical property tests and microstructural analysis. The results showed that the pipeline exhibited cross-linking as the main aging mechanism after being in service for 0e18 years. The aging degree and law of the inner and outer surface of the pipeline were compared, and the observed mechanism of both surfaces was explained. After 18 years in service, the elongation at the break of the pipe decreased by 16.2%, and the toughness of the matrix in the main collapse area of the tensile sample was the fundamental reason responsible for changes in the mechanical properties. Finally, after 18 years in service, the oxidation induction time of the pipeline was 25.7 min, which was 28.5% higher than the national standard value. There were no potential safety hazards during continuous long-term service. The results of this paper provide reference data and theoretical guidance for the aging process study of buried polyethylene pipelines. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of soil liquefaction‐induced displacement on buried pipelines critical to the serviceability of buildings, including those for potable water and natural gas. The emphasis was on the service lines connecting distribution mains and buildings due to their higher vulnerability. Two types of forced displacement tests were conducted on full‐scale physical models of buried service lines. One simulated the uplift or subsidence of distribution mains as the soil surrounding the pipelines is completely liquefied, while the other simulated the building settlement due to partial loss of foundation bearing capacity in various conditions of surrounding soil. The longitudinal strains, deflection, and possible leakage of pipelines were monitored during these tests. The results showed that sufficiently large displacement could cause yielding and pulling out from the joint of the pipe. However, high pipe flexibility and joint strength provided adequate resilience of buried pipelines to these damage modes. The corrugated section of stainless‐steel pipe was also verified to reduce strain in the pipeline. Additionally, when a pipeline was subjected to building settlement, liquefaction of surrounding soil or not led to different strain distribution and deflection along the pipeline. Local buckling of the pipe near the loaded end was induced in non‐liquefied cases due to the combination of forced displacement and soil reaction. These findings give a better knowledge of the resistance performance of buried pipelines against liquefaction‐induced displacement. [ABSTRACT FROM AUTHOR]

This study aims to reveal the deformation characteristics of buried pipelines and the effects of various parameters on settlement displacement using the analytical analysis method. A simplified mechanical model for the settlement displacement of buried pipelines is proposed with the theory of the Winkler model, and the sensitivity impacts of various parameters are performed by comparing them with those given by other cases. The rationality of the proposed approach is verified by a comparison with previous cases, and it also turned out that the present method performed better than the other two methods in the literature in its overall tendency of settlement displacement and error precision. The parameter analysis results of this study indicate that the maximum settlement displacement of the buried pipelines only increases linearly with the increase in ground displacement. Other parameters such as the subgrade modulus and calculated length increase to a certain threshold; the maximum settlement displacement will remain stable. However, the diameter and elastic modulus of the pipelines only have a small effect on the maximum settlement displacement of the pipelines, so they are not a sensitive factor and these effects can be ignored. In addition, an engineering example of pipeline deformation in a deep foundation pit from open-cut excavation is researched to verify the practicality of this present method. [ABSTRACT FROM AUTHOR]

1999 Marmara depremi sonrası Sakarya ili içme suyu şebekelerinin bir kısmında ciddi hasarlar oluşmuş, kanalizasyon şebekelerinin ise neredeyse tamamı hizmet veremez duruma gelmiştir. Bu çalışmada, Sakarya ili altyapı sistemlerinden içme suyu temin ve dağıtım şebekelerinin büyük bir bölümünü oluşturan gömülü boruların sismik tehlikeler karşısındaki hasar görebilirlikleri, Hazards US (HAZUS) metodu ile analiz edilmiştir. Gömülü boruların olası depremlere karşı hasar görebilirliklerinin analizinde kullanılan en büyük yer hızı, klasik olasılıksal deprem tehlike analizi yardımıyla belirlenmiştir. Hasar görebilirlik analizlerinde kullanılan zemin sınıfları, il genelinde 2044 adet noktadan alınan sismik veriler yardımıyla hesaplanmıştır. Sakarya ili içme suyu boru envanteri oluşturulup tüm borulara coğrafi bilgi sistemleri yardımıyla hasar görebilirlik parametreleri tanımlanmıştır. Analizler sonucunda tüm borular için hasar görebilirliği ifade eden hasar onarım oranları elde edilmiş ve borular hasar onarım oranlarına göre sınıflandırılmıştır.

Damage or deterioration of water distribution or storm water drain pipeline systems create a problem of leakage, which has the potential to erode its surrounding soil. This erosion, if not detected in time, can form a large cavity in the ground and consequently results in catastrophic failure. This paper presents a detailed review of soil erosion due to damaged buried pipe using experimental and numerical evidence available in the literature. Herein, erosion is explained using two different flow possibilities, namely, infiltration and exfiltration. A comprehensive discussion on the method of investigation and the erosion mechanism, along with the governing parameters used in the investigation and their challenges, are presented. This review paper also discusses two other issues, that is, the rate of erosion and the volume of cavity formed due to erosion. Both the issues seem to be governed by the hydraulic gradient in the soil, the size of the defect in the pipe and the size of soil particles surrounding the defect. Important empirical and analytical methods which are used to predict the size of the cavity as well as the leakage rate and pressure drop, are also discussed. The location and size of the cavity seems to be highly dependent on the groundwater level. [ABSTRACT FROM AUTHOR]

The uplift effect induced by soil liquefaction on buried pipelines that are critical to the serviceability of buildings, including potable water, natural gas, and sewage pipelines, was experimentally investigated. A full‐scale physical model of pipelines buried in liquefiable ground comprising distribution mains and service lines that connect distribution mains and buildings was built. Shaking table tests were conducted on this model with actual earthquake records utilized as the input motions. The performance of gravel as pipe ditch backfill for mitigating the liquefaction‐induced uplift was also evaluated. During the tests, accelerometers and piezometers were installed in free‐field (FF) soil and around the pipelines to reveal the pipeline–soil interaction and the soil liquefaction development. Wire potentiometers were also utilized to monitor any uplift or subsidence of the pipelines. Results indicate that the distribution mains for natural gas and sewage experienced an uplift during liquefaction of ground specimen. The excess porewater pressure buildup level around the uplifted pipelines was generally lower than that in FF soil and was even lower on top of the pipeline circumference, which may be attributed to the pipeline–soil interaction. Furthermore, the practicability of an existing simplified model for anti‐uplift stability assessment and its corresponding uplift force estimation were examined based on aforementioned observations. The findings indicate that the uplift effect for large‐diameter pipelines may be underestimated by simply using this simplified model. This research can be used as a reference for the seismic design of buried pipelines, which is beneficial for disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

Buried pipelines are one method of conservation transfer for widely used gases such as natural gas and hydrogen. The safety of these pipelines is of great importance because of the potential leakage risks posed by the flammable gas and the special properties of the hydrogen mixture. Estimating the leakage behavior and quantifying the diffusion range outside the pipeline are important but challenging goals due to the hydrogen mixture and presence of soil. This study provides essential information about the diffusion behavior and concentration distribution of underground hydrogen and natural gas mixture leakages. Therefore, a large-scale experimental system was developed to simulate high-pressure leaks of hydrogen mixture natural gas from small holes in three different directions from a pipeline buried in soil. The diffusion of hydrogen-doped natural gas in soil was experimentally measured under different conditions, such as different hydrogen mixture ratios, release pressures, and leakage directions. The experimental results verified the applicability of the gas leakage mass flow model, with an error of 6.85%. When a larger proportion of a single component was present in the hydrogen-doped natural gas, the leakage pressure showed a greater diffusion range. In addition, the diffusion range of hydrogen-doped natural gas in the leakage direction was larger at 3 o'clock than that at 12 o'clock. The hydrogen blend carried methane and diffused, which shortened the methane saturation time. Moreover, a quantitative relationship between the concentration of hydrogen-doped natural gas and the diffusion distance over which the hydrogen-doped natural gas reached the lower limit of the explosion was obtained by quantitative analysis of the experimental data. • A leak device for buried pipelines mixed with hydrogen natural gas was built. • The overhead pipe leakage formula is applicable to buried pipeline leakage. • Diffusion form of hydrogen-blended natural gas. • The variation of the concentration of hydrogen-doped natural gas. • Gas leak diffusion quantitative relationship. [ABSTRACT FROM AUTHOR]

Permanent ground deformation induced by surface faulting can seriously threaten the structural integrity of buried pipelines. The failure mode of fracturing in pipe wall is somewhat difficult to be simulated by the classical finite element method. In this work, brittle damage of buried pipelines subjected to different dip-slip faults is investigated by using peridynamics, where the pipes are characterized as peridynamics shell structures and the surrounding soil is simulated as Winkler springs. Three sets of experiments are simulated using the proposed modeling strategy, and good agreements between experimental and numerical results are achieved, in terms of progressive brittle damage features (deformation and crack patterns). The first crack initiates under a certain fault displacement, and then it propagates inwardly to penetrate through the cross section on the footwall side. A new crack then occurs on the other side in a later stage. Pipeline failure is more prone to occur within the zone of three times the pipe diameter from the fault plane, showing three broken segments by the two dominant cracks eventually. Parametric study suggests that reverse faulting is more harmful to the pipeline than normal faulting. The most unfavorable dip angles for pipelines under normal and reverse faulting are 65° and 75°, respectively. The pipeline with a thicker pipe wall or a higher critical energy release rate, being buried in a smaller burial depth or a looser sand condition, shows a higher capacity to resist the dip-slip fault. [ABSTRACT FROM AUTHOR]

After the 1999 Marmara earthquake, serious damages occurred in some of the drinking water networks of Sakarya province, and almost all of the sewerage networks became inoperable. In this study, the vulnerability of buried pipes, which constitute a large part of the potable water supply and distribution networks of the infrastructure systems of Sakarya province, against seismic hazards were analyzed by the Hazard US (HAZUS) method. The maximum ground velocity used in the analysis of the vulnerability of buried pipes against possible earthquakes was determined with the help of classical probabilistic earthquake hazard analysis. Soil classes used in vulnerability analysis were calculated with the help of seismic data taken from 2044 points throughout the province. Sakarya province potable water pipe inventory was created and vulnerability parameters were defined for all pipes with the help of geographic information systems. The HAZUS method, which is frequently used in the literature, was used for pipe vulnerability analysis. As a result of the analysis, damage repair rates expressing the vulnerability of all pipes were obtained and the pipes were classified according to their damage repair rates. [ABSTRACT FROM AUTHOR]

Faults have large impact on the mechanical behavior of soil in pipeline's construction. These pipelines have been embedded to supply vital resources such as water, oil, and gas for consumers. To prevent damage, it is highly recommended not to construct pipelines around active faults. However, it is generally inevitable to cross the fault due to wide extension of pipelines. In this paper, a numerical analysis and parametric study on an underground water pipeline in Tehran, Iran, under the fault-induced displacement is presented. It is important to note that the main focus of this study is on elbow components which are the most critical sections in pipeline systems. The effects of crossing angle, distance to elbow and various soil properties on the elbow response are investigated. It is aimed at finding a safe regulation to embed pipelines with the lowest level of risk expected in elbow components after fault movement. The results show that the elbow component does not suffer serious damage when the crossing angle is 90°, provided they are not located in the close vicinity of the fault rupture surface. However, when the crossing angle decreases to 60 and 45 degrees, these components are much more vulnerable. [ABSTRACT FROM AUTHOR]

Development and population growth have made using shallow buried pipes in urban areas, highways, and subways inevitable. In this study, the performance and behavior of shallow unplasticized polyvinyl chloride (uPVC) pipes buried in sand reinforced with PET (polyethylene terephthalate) bottles produced by the end consumer filled with soil under static loads were investigated. The bottle reinforcement mattress filled with soil was vertically installed above the buried uPVC pipe inside the soil bed at the required depth; after that, backfilling was performed. The effects of the relative density of soil, placement depth, and the width of the soil-filled bottle-reinforced block were examined. The increase in relative density has shown a noticeable decrease in footing surface settlement and load transferred to the buried pipe. The test results have shown significant improvement in the ultimate bearing capacity of bottle-reinforced soil with a reduction in surface settlement. The backfill reinforced with soil-filled bottle block has shown a 71% improvement in ultimate bearing capacity. Additionally, the improvement in bearing capacity increases as the placement depth decreases and width increases. The optimum depth of placement and width of the bottle-reinforced mattress were 0.50 and 2.08 B. The proposed soil reinforcement method may be a good and relatively inexpensive alternative to traditional geosynthetic reinforcement while providing geotechnical and environmental benefits. [ABSTRACT FROM AUTHOR]

During long-term service, buried pipelines are subjected to complex combined loads, including internal and external loads and pipe–soil interactions. In this paper, a multisensor monitoring network is proposed for the structural health monitoring (SHM) and performance assessment of buried metallic pipelines in a complicated stress state. However, in general, longitudinal bending stress and axial thermal stress cannot be directly obtained by separately considering each information source (i.e. measured longitudinal strain and temperature differentials). Therefore, a Bayesian fusion-based estimation method of stress states and a physics-based data fusion method for calculating longitudinal stresses are presented. A field application with construction and operation phases was carried out to investigate the efficiency of this monitoring scheme and data fusion method. The results illustrated that the proposed method successfully estimated and calculated the longitudinal bending stress and axial thermal stress. The distribution of equivalent stress was obtained, and the structural performance of the pipeline was evaluated. Notably, the measured data showed significant longitudinal bending stress caused by overburden loads, uneven pipe trenches and foundation settlements during the construction phase, which are not considered in classical stress calculation models and current design codes. This practical project provides strong evidence for the motivation of this paper. [ABSTRACT FROM AUTHOR]

In order to evaluate the damage characteristics of buried natural gas pipelines with circular dent defects subjected to blast loading, based on pressure–impulse damage theory, explosion experiment and numerical simulations were implemented to evaluate the damage of a natural gas with circular dent defects buried in soil under blast loading in this research. The ALE method was used to develop a coupled pipeline-soil simulation model using LS-DYNA software, and the validity of the established model was verified correctly compared with experimental results and empirical theory equations calculations. Furthermore, according to regulations in the Assessment and Management of Pipeline Dents (American Petroleum Institute Recommended Practice 1183), the effect with different circular dent defect diameter on the mechanical properties of natural gas was also investigated and analysed. The results showed that, under the blast loading, plastic deformation happened on the surfaces of the pipeline facing the explosive, and the high-stress zone appeared in the circumferential direction with 32.27°. The range of the high-stress zone firstly expanded along the axial direction of the pipelines and then along the circumferential direction. The larger diameter of the circular dent defects had, which resulted in a failure at the defects under the condition of the depth of the defects keeping constant. The effect of the size of defect diameter on the amount of pipeline deformation was further investigated, and the mathematical formula described the maximum plastic deformation with different defect diameter was established. Meanwhile, a finite element model of pipeline with a diameter of 457 mm was established for numerical analysis, which implied that the larger diameter of pipeline with the same defect had, the lower risk of pipeline in failure subjected to blast loading had. And through mathematical analysis and considering the feasibility of the actual situation, the curve described the maximum plastic deformation of the natural gas pipeline with three different defects varying in diameter were established respectively. In addition, a formula to express the relationship between pipeline defect diameter and maximum plastic deformation was established, which can effectively predict the critical plastic dent deformation of pipelines with different defect diameter subjected to blast loading. Besides, based on the pressure-pulse damage theory and with the damage assessment criterion of dent depth–dent length ratio of 0.072, the pressure–impulse diagrams of buried natural gas pipelines with defect diameters of 30 mm, 40 mm and 50 mm were defined, which can be used to predict the damage of pipelines with different defect diameters. Moreover, with the pressure–impulse damage evaluation curves, mathematical formula for the buried natural gas pipeline with the circular defects were established. Furthermore, the critical circular defect diameters with 30 mm was confirmed and the unique formula was also established, which could be effectively used to evaluate the safety of buried natural gas pipelines with the critical circular defects. [ABSTRACT FROM AUTHOR]

This study aims to reveal the deformation characteristics of buried pipelines and the effects of various parameters on settlement displacement using the analytical analysis method. A simplified mechanical model for the settlement displacement of buried pipelines is proposed with the theory of the Winkler model, and the sensitivity impacts of various parameters are performed by comparing them with those given by other cases. The rationality of the proposed approach is verified by a comparison with previous cases, and it also turned out that the present method performed better than the other two methods in the literature in its overall tendency of settlement displacement and error precision. The parameter analysis results of this study indicate that the maximum settlement displacement of the buried pipelines only increases linearly with the increase in ground displacement. Other parameters such as the subgrade modulus and calculated length increase to a certain threshold; the maximum settlement displacement will remain stable. However, the diameter and elastic modulus of the pipelines only have a small effect on the maximum settlement displacement of the pipelines, so they are not a sensitive factor and these effects can be ignored. In addition, an engineering example of pipeline deformation in a deep foundation pit from open-cut excavation is researched to verify the practicality of this present method.

Excavation-induced ground movements can have a detrimental influence on adjacent structures and services. These complex soil–structure interactions are affected by a range of factors such as ground conditions, excavation sequence, and the characteristics of the structures. Considerable prior research has been concerned with understanding the ground response during excavation and in evaluating the potential damage to adjacent facilities. A number of case histories have been reported worldwide. Finite-element analysis can be effective in providing insight into the response of the ground and adjacent structures during the entire construction process. Previous studies have shown that observed excavation behavior (e.g., ground movements and retaining wall deformations) can be captured reasonably well in finite-element analysis, provided that certain key modeling aspects are appropriately addressed. This paper extends a previous deep excavation case study in greenfield conditions (i.e., without adjacent buildings and utilities included in the analysis), focusing particularly on the excavation-induced settlements of nearby buildings and buried pipelines. Sensitivity analyses have been conducted to investigate the effects of several aspects on the computed settlements of buildings and pipelines, such as (1) building weight, (2) building stiffness, (3) building foundation type, (4) ground improvement measures, and (5) geometries and material properties of pipelines. Conclusions are drawn for future applications. [ABSTRACT FROM AUTHOR]

Pipelines are widely used to transport water, wastewater, and energy products. However, the recently published American Society of Civil Engineers report revealed that the USA drinking water infrastructure is deficient, where 12,000 miles of pipelines have deteriorated. This would require substantial financial investment to rebuild. Furthermore, the current pipeline design practice lacks the guideline to obtain the optimum steel reinforcement and pipeline geometry. Therefore, the current study aimed to fill this gap and help the pipeline designers and practitioners select the most economical reinforced concrete pipelines with optimum steel reinforcement while satisfying the shear stresses demand and serviceability limitations. Experimental testing is considered uneconomical and impractical for measuring the performance of pipelines under a high soil fill depth. Therefore, a parametric study was carried out for reinforced concrete pipes with various diameters buried under soil fill depths using a reliable finite element analysis to execute this investigation. The deflection range of the investigated reinforced concrete pipelines was between 0.5 to 13 mm. This indicates that the finite element analysis carefully selected the pipeline thickness, required flexural steel reinforcement, and concrete crack width while the pipeline does not undergo excessive deformation. This study revealed that the recommended optimum reinforced concrete pipeline diameter-to-thickness ratio, which is highly sensitive to the soil fill depth, is 6.0, 4.6, 4.2, and 3.8 for soil fill depths of 9.1, 12.2, 15.2, and 18.3 m, respectively. Moreover, the parametric study results offered an equation to estimate the optimum pipeline diameter-to-thickness ratio via a design example. The current research outcomes are imperative for decision-makers to accurately evaluate the structural performance of buried reinforced concrete pipelines. [ABSTRACT FROM AUTHOR]

Studying dynamic response of buried pipelines under blasting loads has great significance to the design of blasting construction near the pipelines and safety protection of the pipelines. Numerical study was used to reveal the dynamic response law of vibration velocity, strain, stress, and pressure of polyethylene（PE） pipelines with four kinds of the same standard dimension ratio（the ratio of outer diameter to thickness of pipe wall）. The results show that the transverse vibration has the greatest influence on the cross section of PE pipe facing the explosion centre, and the axial vibration has the greatest influence on both sides of the cross section of PE pipe facing the explosion centre. The influence of compressive strain is greater than that of tensile strain, and the pipeline is easy to be damaged. Within the allowable error range, the dynamic response parameters（peak vibration velocity, peak circumferential compressive strain and peak pressure） of the four kinds of PE pipes with the same standard size can be predicted by the fitting formula considering site coefficient and attenuation coefficient. [ABSTRACT FROM AUTHOR]

Türkiye is known for its intricate tectonic structure and high seismic activity, which makes in-depth research on earthquakes necessary. This research paper presents a multifaceted examination of earthquake impact in Türkiye, encompassing critical elements of seismic vulnerability with a special focus on the latest twin earthquake of February 6, 2023. Firstly, a three-dimensional finite element (FE) analysis has been conducted to explore the buried pipeline behavior under left-lateral strike-slip faults. Secondly, making use of the earthquake data from 1976 to 2023, a new Newmark displacement-based model has been proposed which predicts co-seismic landslide displacement. Finally, new magnitude conversion relations are developed in the generalized moment magnitude scale (M wg) for Türkiye using three statistical regression techniques. The maximum tensile strain was found to be around 2.0% based on the findings of the 3D numerical study of an underground pipe that was subjected to left-lateral strike-slip fault movement. The proposed co-seismic landslide displacement model was developed based on moment magnitude, yield acceleration, and peak ground acceleration, which yields an R-squared value of 0.93. Outcomes of the magnitude conversion study depicted that the improved general orthogonal regression (IGOR) relationships developed in this study performed better than the other conventional methods of regression. Also, the proposed regional relations based on M wg scale perform better than global relations as they provide closer values to the observed ones. By offering a comprehensive perspective on seismic impact, the research lays the groundwork for upgraded predictive methods and refined seismic design considerations. The proposed models and conversion relations contribute to the strengthening of critical infrastructures, providing a forward-looking approach to enhance preparedness and resilience against earthquake disasters in Türkiye. • Examined the response of buried pipelines under left-lateral strike-slip fault. • Proposed a new empirical model for co-seismic landslide displacement for Türkiye. • Developed magnitude conversion relations in the M wg scale for Türkiye. [ABSTRACT FROM AUTHOR]

A novel mitigation technique is proposed in this paper to effectively improve the safety and integrity of buried pipelines subjected to ground deformation and to mitigate the detrimental effects of ground deformation on the pipe. This technique involves the installation of special geomaterial blocks (SGBs) adjacent to the pipe. The SGB consisting of multiple layers of hollow plastic boxes placed between layers of high-density expanded polystyrene (EPS) geofoam blocks forms a thick sandwich panel structure, which is oriented such that its orthotropic mechanical property allows the pipe to move laterally without developing significant reactions against the soil. A summary of past mitigation techniques and the method proposed in this study are first presented. Large-scale experimental testing used to assess the beneficial effects of the SGB on the pipe response when subjected to lateral and oblique displacements is then presented, followed by a simplified finite element model proposed to numerically simulate the pipe-SGB-soil interaction under lateral soil displacement. The results confirm that the proposed remediation method can significantly reduce the soil-pipe interaction force. Furthermore, the proposed beam-based numerical model that can be used in engineering design predicts well the lateral load-deformation response of the system. [ABSTRACT FROM AUTHOR]

It is very important to calculate the interference of high voltage direct current (HVDC) grounding current with pipelines accurately and take proper protective measures to ensure energy transmission safety. There is still a lack of systematic research into related prediction methods that consider the nonlinear polarization on the interface between the soil and pipelines. In this paper, a methodology is proposed for calculating the coupling voltage and current on buried pipelines induced by grounding currents that accounts for nonlinear polarization based on the method of moments (MoM) and the finite element method (FEM). The validity of the proposed mathematical model is verified by a scale experiment. The interference distribution characteristics under different parameters are analyzed using the proposed method. The results show that the relationship between the maximum leakage current density and the electrode grounding current satisfy the linear function. The corrosion area becomes more concentrated as the grounding current increases. The corrosion area range increases substantially as the distance increases, whereas the influence degree decreases substantially. Both the maximum leakage current density and corrosion risk area are positively correlated with the soil resistivity. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical analysis of the uplift resistance of pipelines buried in reinforced soil. The behavior of the system is studied using a set of laboratory experiments. The pull-out forces of some reinforcing pipelines are the most important factors affecting the uplift resistance. Buried elements such as pipelines that have high pressure fluids or are under high temperature need to be reinforced in order to increase their pull-out resistance. One of the efficient methods of reinforcement is increasing the involvement between pipe and soil by using geogrids and anchors. The grid-anchor is a recent method for increasing the pull-out resistance of soil, and is the method used in this study. The digital image correlation or particle image velocimetry (DIC/PIV) method is used for measuring the displacement in the field of experimental mechanism. We also examined the influence of parameters affecting the soil. An experimental study was performed to investigate the uplift resistance of the pipelines buried in sand reinforced with this system. The experimental results demonstrate that, for the pipes with a diameter of 50 mm, the grid-anchor system of reinforcement can increase the uplift capacity 2.4 times compared with the conventional geogrid and 4 times compared with nonreinforced sand. In the numerical modeling, likewise, 23 experiments were back-analyzed using the software FLAC-3D. It became known that experimental tests compare well with the numerical results. [ABSTRACT FROM AUTHOR]