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Copyright of Corrosion & Protection in Petrochemical Industry is the property of Corrosion & Protection in Petrochemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper introduces a new algorithm that can determine the location of the compromised pipeline and its path while also examining the impact of the sensor array's parameters on imaging outcomes. Results show that the sensor array rotates at a specific angle relative to the pipeline, and the pipeline's path remains visible. Experimental trials using a vibration sensor to capture vibrational data indicate that at an acceleration of water reaching 9 m/s2, the maximum output analog voltage (corresponding to the leakage point) reaches 35.6 mv, with the analog voltage decreasing as one moves away from the main leakage point, thereby validating the viability of the new algorithm. Rotating the pipeline at a certain angle can result in an output analog voltage of up to 37.4 mv, and the presence of the leaking pipe and its path continues to be observable. [ABSTRACT FROM AUTHOR]

The drainage pipelines put into use in the early stage have been faced with various problems with the rising of groundwater level and the increase of service time of drainage pipelines in Beijing, among which the failure of drainage pipeline structure is particularly prominent. In order to study the failure mechanism of the drainage pipeline structure, the causes of the failure of the drainage pipeline structure were analyzed based on the site investigation on the diseases of the existing drainage pipelines in Beijing. Three key factors including the backside empties, the change of groundwater level and the load of ground vehicles were obtained, and the influences of these three factors on the failure mechanism of pipelines were further investigated. Based on the parameters of a practical project, a series of numerical simulations were carried out to calculate and analyze the related parameters of pipelines such as horizontal displacement, vertical displacement and safety factor so as to investigate the failure mechanism of pipelines. The results show that the key of drainage pipeline accidents is pipeline leakage, and the main reasons are living environment, construction disturbance, bearing capacity, respectively. Moreover, 70% of pipeline accidents are caused by pipeline living environment, and 25% of that are caused by construction disturbance, while only 5% are caused by pipeline itself. Besides, the natural environment and construction quality problems easily lead to the formation of a small range of non-dense areas around the pipeline, which then evolve into serious unstable bodies such as voids. The appearance of voids between the drainage pipelines and the soil will lead to a large reduction in the safety factor of pipeline structure. The rise of groundwater level will affect the safety performance of the drainage pipeline structure and reduce the safety factor of the using drainage pipeline. When the road vehicle load is orthogonal to the drainage pipeline, the influence of the vehicle load on pipeline structure is the most, and the safety factor of the upper part of the structure is significantly smaller than that of other conditions. Therefore, more attention should be paid to the influence of voids between the drainage pipelines and the soil on the structure of drainage pipelines. And line, the main measurement and treatment measures should be adopted for the drainage pipeline orthogonal to the ground traffic to maintain the safety of the pipeline structure and prevent leakage and disease. [ABSTRACT FROM AUTHOR]

In the rapid development of urban construction, underground pipelines play a crucial role. However, the current underground pipelines have poor association with relevant management departments, and there are deficiencies in data completeness, accuracy, and information content. Managing and sharing information resources is relatively difficult, transforming the constructed 3D underground pipeline geographic information systems into an 'Information silo'. This results in redundant construction and resource wastage of underground utilities. The complex distribution characteristics of underground utilities make rapid batch modeling and post-model maintenance challenging. Therefore, researching a 3D spatial data fusion model for urban underground utilities becomes particularly important. Given the above problem, this paper proposes a spatial data fusion model for underground pipeline scene modeling. It elaborates on the geometric, semantic, and temporal characteristics of underground pipelines, encapsulating these features. With underground pipeline objects as the core and pipeline characteristics as the foundation, a spatial data fusion model integrating multiple characteristics of underground pipelines has been constructed. Through software development, the data model designed in this paper facilitates rapid construction of underground pipeline scenes. This further enhances the consistency and integrity of underground pipeline data, enabling shared resources and comprehensive supervision of facility operations on a daily basis. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the rapid development of urban construction, underground pipelines play a crucial role. However, the current underground pipelines have poor association with relevant management departments, and there are deficiencies in data completeness, accuracy, and information content. Managing and sharing information resources is relatively difficult, transforming the constructed 3D underground pipeline geographic information systems into an ‘Information silo’. This results in redundant construction and resource wastage of underground utilities. The complex distribution characteristics of underground utilities make rapid batch modeling and post-model maintenance challenging. Therefore, researching a 3D spatial data fusion model for urban underground utilities becomes particularly important. Given the above problem, this paper proposes a spatial data fusion model for underground pipeline scene modeling. It elaborates on the geometric, semantic, and temporal characteristics of underground pipelines, encapsulating these features. With underground pipeline objects as the core and pipeline characteristics as the foundation, a spatial data fusion model integrating multiple characteristics of underground pipelines has been constructed. Through software development, the data model designed in this paper facilitates rapid construction of underground pipeline scenes. This further enhances the consistency and integrity of underground pipeline data, enabling shared resources and comprehensive supervision of facility operations on a daily basis.

Introduction. The long network of pipelines on the territory of our country needs timely and high-quality repairs. The entrenching tool used so far increases the complexity of work on the overhaul of pipelines, which forces to create solutions for mechanizing the process of digging the pipeline. The purpose of the study conducted in this article is to determine the performance and total torque of the working equipment of the excavator. A general view of the working equipment with the designation of the positions necessary for the study is given. Methods and materials. The concept of specific values of torque and power per one cutter of working equipment has been introduced. The dependencies of the total productivity of the cutters and the torque of the cutters are established. Due to the peculiarity of the design of the working equipment, each of the dependencies is considered separately for the front and rear incisors. The surfaces that reflect the influence of the angular velocity of rotation of the milling head and the angle of installation of the cutters on the parameters under the study are constructed. Results. Based on the obtained dependence of the total torque of the milling working equipment, a nomogram was compiled. By setting the number of N cutters, the speed of rotation of n working milling head and the number of strokes of the DorNII (Road Research Institute) striker, it is possible to determine the required torque of the hydraulic motor. Сonclusions. According to the results of the theoretical study of the process of cutting soil with the help of excavator milling working equipment, the dependencies of the total productivity and total torque of the working equipment were established. The constructed graphic dependencies help to determine the degree of influence of design and operating parameters on the work process. The created nomogram is recommended for use in the design of working equipment.

Relevance. Determined by the need for geotechnical monitoring in the areas of distribution of permafrost soils for underground pipelines. The geotechnical system “permafrost soil – underground pipeline” is subject to the influence of exogenous geological processes during operation, cyclical changes in the state of soils of the seasonal layer of thawing and freezing, thawing of permafrost soils from the thermal effect of the pipeline, changing the plan-altitude position. The variety of schemes for interaction of the pipeline body with varieties of lithological structure of permafrost soils along the route should be worked out in detail at the design stage and also assessed in detail during geotechnical monitoring of the pipeline. The lack of regulatory requirements for the monitored parameters of underground pipelines leads to the use of non-standardized and varied monitoring networks from project to project. The lack of standard values ​​for the maximum deformations of an underground pipeline leads to the need to use calculation methods for determining the maximum deformations of the base and pipeline. The authors proposed the use of a comprehensive methodology for calculating underground pipelines, developed by employees of JSC TomskNIPIneft to determine the maximum permissible deformations of the pipeline at each point of the route with the presence of permafrost soils at the design stage, with further use of the results obtained as a controlled criterion when conducting geotechnical monitoring. Aim. To determine the controlled parameters for geotechnical monitoring of underground pipelines in the cryolithozone at the operational stage based on the application of a comprehensive methodology for calculating underground pipelines, as well as the formation of requirements for the system of information points. Methods. Review of the regulatory framework for geotechnical monitoring, analysis and evaluation of the applied methods and designs for monitoring underground pipelines, analysis of a comprehensive methodology for calculating underground pipelines in relation to the purposes of geotechnical monitoring. Results. Based on the results of the review of regulatory and technical documentation, the authors have revealed a lack of specification of methods, equipment, volume of the geotechnical monitoring network and frequency of pipeline monitoring, as well as the requirement for the use of the calculation method of limiting deformations and the lack of description of possible methods. A detailed analysis of the complex methodology for pipeline calculations, developed at JSC TomskNIPIneft, substantiates its use for geotechnical monitoring purposes, and notes the advantage of the methodology in the detail of the obtained limit values ​​of deformation with an accuracy of one meter along the axis of the pipeline route. The authors studied the methods and designs used for monitoring deformations of underground pipelines and established the compatibility of using a complex methodology with any design and method of monitoring. The paper introduces the list of the main monitored parameters and justification for the scope of the geotechnical monitoring network for underground pipelines.

Relevance. Determined by the importance of predictive modeling of thermal state of pipeline transport facilities located in the permafrost zone. Prediction of geocryological effects is possible through computer simulation of heat and mechanical interactions between a pipeline and a soil medium. Such simulators use data on climatic and geocryological conditions and processes, as well as the information about design and process-dependent parameters of the pipeline, data on its spatial positioning. The presence of various factors influencing heat and mass transfer, as well as the complexity of their numerical simulation, can lead to incorrect design decisions. Such decisions in their turn are always associated with a loss of mechanical safety in an underground pipeline operation. To eliminate this design problem, it is necessary to correctly take into account and adopt the most relevant methods for modeling processes and soil characteristics. Aim. To conduct an analytical comparison of the results of thermal engineering calculations of one section of the route with insular permafrost in order to identify the influence of the model initial parameters on the stress-strain state of the pipeline. Methods. Analyzing the results of engineering surveys for the object of study, conducting a number of numerical calculations, and factorial comparison of the calculation results. Results. At the first stage, the authors have selected the route section of the underground pipeline corresponding to the purpose of the research, the factors influencing the results of thermal modeling. These factors will be considered in this study. At the second stage, the authors carried out modeling of 30 calculation models of one route section with a different set of input data. A factorial comparison of the effect of heat engineering calculation on the results was carried out. At the last stage, the authors carried out the strength calculations of all options for the selected section of the pipeline route as a resulting indicator of the influence of factors.

Introduction. During the overhaul of the pipeline to remove the soil under the pipe, a trench tool is currently used. The new technology of excavation of soil under the pipeline proposed by the authors, which provides for the use of replaceable milling working equipment for a hydraulic excavator, makes it possible to increase the speed of repair work. The purpose of the article is a theoretical study of the process of interaction between the structural elements of milling equipment and the developed soil.Methods and materials. Based on the basic provisions of the theory of interaction of the working bodies of earthmoving machines with the soil, a mathematical model of the work of the milling working equipment of a hydraulic excavator was created. It makes possible to get the dependence of the resistance forces arising on the cutters of the working equipment, on its design parameters and the physical and mechanical properties of the soil.Results. According to the results of the analysis of the obtained dependence of the torque on the cutting angle and the angular speed of rotation of the milling head, it was found that the greatest influence on the torque required to overcome the forces of soil resistance and the drive of the working body is exerted by the angular speed of rotation of the milling head. The minimum value of the torque in the study area 50 N·m is observed at the point where the cutting angle of the soil is 45º, and the angular speed of rotation of the milling head is 4 rad/sec. The maximum torque 215 N·m was recorded at a cutting angle of 65º and a milling head speed of 10 rad/sec.Сonclusions. According to the results of the theoretical study of the process of cutting soil with the help of the milling working equipment of the excavator, the torque of the hydraulic motor necessary to rotate the milling head was established. The results of the theoretical studies carried out are recommended to be used to calculate the design and operating parameters in the design and creation of an experimental sample of milling working equipment.

In this study, a machine learning-based prediction model was developed using the attribute information of underground pipelines and the history information of ground subsidence in order to predict the risk level of ground subsidence in urban areas. The target area was divided into a grid with sizes of 100m $\times 100\text{m}$ , 300m $\times 300\text{m}$ , and 500m $\times 500\text{m}$ , and the attribute information of underground pipelines in the grid and ground subsidence data were utilized to build a dataset. For input data, the pipeline’s diameter, the number of years used, and density were selected based on the pipeline’s length as the basic unit. Additionally, the risk level of ground subsidence was determined as the output data using historical information. A total of 36 datasets were built according to the conditions, and factors with significant correlation were selected through a correlation analysis of the datasets. The developed datasets were divided into training data and evaluation data. The synthetic minority oversampling technique was used to resolve the data imbalance. The model performance evaluation indexes used in this study were F1-score and AUC(Area Under the Curve). The performance of each model was compared, and the comparison results showed that a model that applied a preprocessed dataset with 500m $\times 500\text{m}$ grid size, 10 years in use, 100mm pipeline diameter, and 1–2 ground sinks in Level 1 risk range to the LGBM(Light Gradient Boosting Model) classifier derived the best evaluation indexes(F1-Score:0.750, AUC:0.840). The map was found to be effective for predicting the risk level of ground subsidence in urban areas.

Online monitoring of natural gas in urban underground space has proven to be an effective method for resolving minor leakage and explosion accidents in urban low-pressure natural gas pipelines. However, the harsh environment of urban underground space is often accompanied by the generation of biogas, whose components are more similar to those of natural gas, causing great disturbance to early warning of natural gas leakage. This study correlates the biogas generation principle and its transport law with human activities and environmental changes, analyzes and extracts the characteristics of the natural-gas-biogas CH 4 concentration using big data analysis technology, and establishes a natural-gas-biogas sample database. The imbalance between positive and negative samples in the database is addressed by two oversampling techniques. The models trained by two different machine learning algorithms were then evaluated. The results of the study are summarized as follows: (1) There are daily and annual cycles in the CH 4 concentration in biogas. The daily trend of biogas in the same manhole is similar, and the biogas in different manholes shows various changes periodically with human activities. Biogas early warnings often occur during the high temperature season (April-September). (2) Features such as period, temperature of alarm, and average concentration over 24 h are positive for improving model accuracy. (3) The combined model of XGBoost and the borderlineSMOTE algorithm has an f-score of 72.7 %, an accuracy of 71.2 %, and a recall of 73.4 %. Compared with the traditional manual classification method, the model proposed in this study can identify natural gas and biogas in a more real-time and accurate manner, reduce the workload of on-site confirmation, and effectively shorten the emergency response time. [ABSTRACT FROM AUTHOR]

In this study, a new mechanical model is proposed to compute earth pressure above a pipeline considering pipe-soil interaction and three-dimensional soil arching effects of cohesive fills, based on the Terzaghi vertical sliding surface theory. In this model, the pipeline was mechanically separated into buried and suspended segments, whose stress distribution and deformation were solved according to the boundary conditions and geometric conditions. Comparisons to both the test data and corresponding finite element codes concretely verify the proposed mechanical model. Then a parametric investigation indicated that the mechanical behavior of the pipe is greatly affected by the size of a subsidence area and the flexural rigidity of the pipe. [ABSTRACT FROM AUTHOR]

Link for citation: Filimonov A.A., Strokova L.A. Assessment of engineering and geocryological conditions of the territory of the operated pipeline route on the Malkhoyakha–Pur interfluve. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 6, рр.163-175. In Rus. The relevance of the work is determined by the importance of trouble-free operation of pipeline transport facilities located in the permafrost zone. Manifestations of dangerous engineering and geological processes during the operation of an underground pipeline can lead to changes in the permafrost soil-pipeline system, which will entail the occurrence of off-design loads on the pipeline body, pipeline failures and accidents. It is required to analyze the activation and development of dangerous geological processes along the pipeline route in order to correctly assess changes in engineering and cryological conditions during pipeline operation. The main aim is to rank sections of the route with developing hazardous geological processes and to identify their impact on the conditions for the further operation of the facility. Methods: analysis of the results of engineering surveys on the object of study and geotechnical monitoring data of the oil and condensate pipeline; evaluation methods for zoning sections of the route. Results. At the first stage of the study, the route was classified, the study areas were identified, and criteria were determined for assessing active hazardous geological processes using the scoring method. At the second stage, the zoning model was determined, the boundary criteria γ (the proportion of identified hazardous geological processes for the section of the route) were designated, taxa were designated, sections of the route were ranked in accordance with the zoning model. The most vulnerable sections of the oil and condensate pipeline route from the point of view of the manifestation of geological processes were identified.

Underground pipelines are the lifelines of a modern city. The precise positioning of underground pipelines is essential to avoid pipeline damage during successive construction above it. However, detecting deep-buried pipelines in soft clayey deposits is challenging. This paper proposes a new method called the surface-to-borehole electromagnetic induction method (SB–EIM) by combining the traditional ground EIM with the magnetic gradient response in a borehole. Firstly, a depth measurement method was established based on the magnetic fl ux response to the applied magnetic field in a borehole. Secondly, a theoretical analysis method was proposed to calculate the pipeline depth and its horizontal position using the measured data. By analyzing the magnetic flux response characteristics at different depths, the relationship between the maximum response point and the spatial location of the target pipeline was determined. Finally, an in-situ test was conducted, and the eff ectiveness of the proposed method was verified. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhengzhou University (Natural Science Edition) is the property of Journal of Zhengzhou University (Natural Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The possibility of partial splitting of the dynamic equations of the linear theory of elasticity for bulk expansion and the components of the rotation vector of medium particles in cylindrical coordinates in the general case of a nonstationary problem is proved. This result is a generalization of a similar fact established by A. Love with a simple harmonic dependence of the named functions on time and two spatial coordinates. An exact analytical solution of the problem on bending vibrations of an elastic space with a circular cylindrical cavity (external Pochhammer–Chree problem) is given. It is shown that the study published by K. Toki and Sh. Takada on this problem does not provide a solution to the posed problem. On the basis of the solution obtained for the external Pochhammer–Chree problem, bending vibrations of an underground pipeline caused by the action of a seismic wave are studied. The results obtained in this case provide, apparently, the first theoretical substantiation of the engineering theory of rigid jamming of the pipeline in the soil for the case of bending vibrations, widely used in regulatory documents on seismic construction. [ABSTRACT FROM AUTHOR]

To ensure the reliable management of the safe operation of an underground pipeline in a chemical industrial park and accurately determine the location of the pipeline leakage point, a precise location method for the leakage point of an underground pipeline in a chemical industrial park based on ultrasonic creeping wave flaw detection and data integration is proposed. In this method, the ultrasonic creeping wave flaw detector is used to detect the underground pipelines in the chemical industry park and obtain the status signals of the underground pipelines in the chemical industry park. The improved K-means algorithm is used to fuse the signals collected by clustering to obtain abnormal signals in the signals; The wavelet transform is used to process the ultrasonic abnormal signals obtained by clustering, extract the local time energy density characteristics of the frequency band, and superimpose the image. By introducing image enhancement factors, the leakage area can be centrally located, the coordinates of the pipeline leakage points can be determined, and the leakage degree can be determined by calculating the sum of the damage probability of each leakage point. The test results show that the clustering effect of this method is good, and the separability measurement indexes are all above 0.925, which can complete the location of single point and multi-point leakage points, and the maximum location error is 11.55 mm. The reliability of the location of the leakage point is high.

The paper considers a set of issues affecting the actual problems of operational repair and restoration work on underground pressure water and drainage pipelines made of various materials that have exhausted their standard service life and are subject to numerous defects in the form of cracks, joint divergences, rust growths, fistulas and others. The aim of the work is to consider trenchless technology as a promising method of repairing dilapidated pipelines, which uses the application of polymer hoses to the inner surface of pipeline networks. The general requirements for flexible polymer sleeves and their characteristics, the scope of application of sleeves, as well as requirements for structural materials used in the production of flexible polymer sleeves are considered as the subject of research. The result of the work is an analysis of the sequence and essence of preparatory operations, including in-line diagnostics and a coding system for the results of visual inspection of pipelines. As conclusions, examples of calculating energy savings during water transportation before and after repair and restoration work at an exemplary facility are given, depending on the technical characteristics of the hoses used, as well as their thickness, depending on the depth of the pipeline.

Copyright of Journal of Shanghai University of Engineering Science / Shanghai Gongcheng Jishu Daxue Xuebao is the property of Journal of Shanghai University of Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Leaks in pipelines caused by acid are destructive to both economic growth and capital which should be avoided at all costs. Damage to underground pipelines is caused by a hard-to-find leak, the unavailability of a real-time monitoring system and the lack of a pipeline history database. The aim of this work is to develop an early warning system to detect acid leaking in the pipeline using Internet of Things (IoT) technology. To detect changes in the pH of acid soil parameters near the pipeline, two mechanisms are required: first, to provide an early warning before the leak is detected and second, to report the occurrence of the leak. The notification system is equipped with three LED indicators, each showing the offline, online and signal detection status. The novelty of the work is a prototype that can detect the acid leak in the pipeline and record the pH values in a database for future research. Using continuous pH monitoring, real-time analysis and a database, this system can detect leaks before they become a major problem. Consequently, the manufacturing industry will benefit from this initiative as it is automated, efficient and cost-effective. [ABSTRACT FROM AUTHOR]

Stationary oscillations of an underground pipeline caused by oblique incidence of a plane seismic wave are investigated. It is shown that an oblique wave can be represented as several longitudinal and transverse waves propagating along the pipeline at higher velocities. The statement of the coupled problem of joint longitudinal vibrations of elastic soil and pipeline is given. The obtained analytical solution of the external problem for the soil leads to a theoretical expression for the force of interaction between the pipeline and the soil, for which only empirical relationships were previously proposed. Solutions for pipelines in supersonic and subsonic modes demonstrate a significantly different nature of their behavior, which should be taken into account in seismic calculations. [ABSTRACT FROM AUTHOR]

• A novel sewer defect classification model based on the vision transformer (ViT) is proposed. • Two cost-sensitive learning algorithms are incorporated to deal with the imbalanced multi-class sewer dataset problem. • The model outperforms several state-of-the-art CNN models in terms of precision, recall, and F1-score. • The model demonstrates the potential of applying the transformer architecture to sewer defect identification. Sewers are a critical component of urban infrastructure, presenting significant challenges in efficiently detecting defects. Currently, Convolutional Neural Networks (CNNs) are widely applied in CCTV inspections for defects in sewers. However, images of these defects commonly suffer from dataset imbalance, and CNNs can only capture local features of images, lacking a comprehensive understanding of the global image and performing poorly in generalizing across imbalanced datasets. Therefore, we introduces a classification model for sewers based on the self-attention mechanism, SViT/CE, tailored for imbalanced datasets, and proposes the SViT/WCE and SViT/FL models. The results demonstrate that the SViT/CE model achieves precision, recall, and F1-score of 53.64%, 58.51%, and 55.97% respectively on the test set. The SViT/WCE model achieves 55.87%, 59.53%, and 57.64%; the SViT/FL model scores 54.13%, 62.91%, and 58.19%. In comparison, the best-performing model among the baseline models scores 41.56%, 42.86%, and 42.02% in precision, recall, and F1-score, respectively, with the SViT series models outperforming the baseline models across all three metrics. The SViT/WCE and SViT/FL models show improvements of 2.06%, 1.02%, 1.67%, and 0.49%, 4.40%, 2.22% over the SViT/CE model in precision, recall, and F1-score, respectively. This study provides an efficient self-attention mechanism model for the classification task of sewer image defects, ensuring the safety and stable operation of urban drainage infrastructure. [ABSTRACT FROM AUTHOR]

Based on the Pasternak model of elastic foundation beams, and combining the effective stress principle of soil and Dupuit hypothesis, the analytical solution of adjacent pipeline deformation in sandy soil caused by single well dewatering is derived. The example calculation results are in good agreement with the results of pumping test and numerical simulation, which verifies the applicability. The law of stress and deformation for the pipeline is studied by parameter analysis. The results show that the influence of soil shear stiffness should not be ignored in the study of soil-pipeline interaction and the pipeline deformation range is approximately equal to the influence radius of dewatering. Pipeline deformation and stress are greatly influenced by dewatering depth and the distance between the pipeline and the dewatering well. Before reaching the critical drawdown, the maximum value of pipeline deformation and bending moments are at the center of pipeline, increasing with the increase of dewatering depth. When the dewatering depth exceeds the critical drawdown, the maximum bending moment will shift outward from the center with the increase of the dewatering depth, resulting in two peak bending moments which are at the intersection of the water level line and at the pipeline. The research results can provide reference for pipeline protection in relevant projects.

The coupled unsteady vibrations of an underground pipeline and elastic soil caused by an inclined fall of a plane seismic wave are studied. The coupled self-similar problems are formulated. An analytical solution of the external problem for the soil is obtained. This solution leads to a theoretical expression for the force of interaction between the pipeline and the soil, for which only empirical relations were previously available. Solutions for pipeline in supersonic and subsonic cases demonstrate significantly different behavior, which should be taken into account during earthquake resistance calculations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-precision detection of the underground pipelines is an indispensable part of the development and construction of cities. At present, the inversion technology for ground-penetrating radar (GPR) data is an effective means of realizing shallow-underground-space visualization in the field of geophysical exploration. However, the traditional full-waveform inversion (FWI) method usually faces the problems of strong nonlinearity of the objective function, high dependence on the initial model, and huge calculation cost. For improving the accuracy and efficiency of GPR data inversion, a wavefield reconstruction inversion (WRI) strategy is used for GPR data imaging to reduce the nonlinearity of the inversion problem and the dependence on the initial model. Then, the frequency weighting strategy and the multi-scale method are adopted to avoid the high-frequency component data dominating the optimization process and enhance the stability of inversion. In this paper, two numerical experiments of pipeline models with different materials and spacing or buried depths verified that the proposed method can effectively reconstruct the subsurface pipelines, and further performance of our algorithm on the field data verified the reliability of high-precision imaging of urban underground pipelines, which shows great potential of application in the field of high-precision detection of the urban underground pipelines. [ABSTRACT FROM AUTHOR]

For long-span structures, such as long bridges and underground pipelines, the loss of correlation of ground movements during an earthquake should be taken into account for seismic analyses. In this paper, longitudinal seismic responses of underground pipelines, which are modeled as distributed mass pipelines with fixed-fixed ends, are derived with a pseudo-excitation method. The seismic excitation is considered a random process and partially correlated. The root mean square (RMS) axial stresses and displacements are compared between pipelines with fixed-fixed and free-free ends. The effects of slenderness ratio and pipe thickness on the seismic responses are also investigated. The results show that the seismic response of fixed-ends and free-ends pipelines matches well when the slenderness ratio is large enough. On the contrary, the boundary conditions should be taken into account for short pipes or pipes with a large external radius. The RMS axial stresses at the midpoint of the pipes decrease with the increase of pipe thickness, and no significant difference is found between fixed-ends and free-ends pipes. [ABSTRACT FROM AUTHOR]

We propose new methods for the analysis of regularities of the kinetics of growth of external corrosion crack in the walls of underground metal pipelines with regard for the given internal pressure and cathodic protection. They are based on the analysis of corrosion currents at the crack tips taking into account the mechanical stresses, Ohmic potential drop, and overvoltage of the anodic dissolution of the metal. We propose an improved method for the evaluation of the service life of underground metallic pipelines in view of the influence of mechanical stresses formed in the vicinity of the crack tip on corrosion currents. It is shown that mechanical stresses lead to a decrease in the service life of the pipeline by a factor of 3.6 as compared with the case where the internal pressure is close to atmospheric. [ABSTRACT FROM AUTHOR]

Ground-penetrating radar (GPR) is widely used in the detection and positioning of underground facilities. Through the inversion analysis of echo signals of GPR, information such as pipe material, burial depth and location of pipelines can be obtained. Unfortunately, underground pipelines are cylindrical, the ladder approximation method used in traditional forward models produces certain errors. In this study, an accurate and efficient numerical model of GPR forward model in underground pipelines is established using symplectic Euler algorithm, graphics processing unit (GPU) acceleration technology and surface conformal technology. With a Ricker wavelet pulse as the GPR source, the convolution perfectly matched layer (CPML) is incorporated in the symplectic Euler algorithm and shown to be effective to truncate the symplectic Euler computational domain. Through the simulation study of different underground pipeline models, GPR image characteristics of the metal pipeline, plastic pipeline and concrete pipeline filled with air and water are obtained. According to the numerical simulation results, parallel conformal symplectic Euler algorithm effectively reduces the false diffracted waves caused by ladder approximation and improves the computational efficiency of the model in metallic and non-metallic media.

The stability of a pipeline jointed to a unit interacting with the surrounding soil is analyzed. The pipeline is subject to axial compression. The stress state of the pipeline body (elastic beam) is directly related to the uplifting of the unit. The axial force at which the stress reaches the critical value is calculated. The influence of the stiffness coefficient (soil conditions) and the location of the unit on the stability of the pipeline are shown. Calculated results for the unit fixed at the middle of the beam (pipeline) and for its asymmetric location are given. The results are presented in the form of curves of the reduced dimensionless frequency and distribution of the longitudinal stress along the beam axis and commented. It is revealed that the asymmetric location of the unit leads to a decrease in the critical force at which stability loss occurs. [ABSTRACT FROM AUTHOR]

Featured Application: Main gas and oil pipelines are critical elements of the world's infrastructure. The integrity of pipelines during earthquakes is a subject of intensive research. At present, underground pipelines' strength to the effect of seismic loads (seismic resistance) is calculated incorrectly. The existing methods do not consider seismic (dynamic) pressure, i.e., the stress normal to the pipeline's outer surface arising from the propagation of a seismic wave in the soil. This leads to an incorrect determination of the pipeline's stress; the longitudinal stress calculations leads to errors of 100% or more. A potential application of the results obtained is the calculation of seismic stability of underground pipelines. The object of the research is an underground straight horizontal pipeline subjected to seismic impact. The research method was analytical. The results were compared with the experimental results of other authors and computer calculations. It was shown that the main disadvantage of the dynamic theory of seismic resistance of underground pipelines is the neglect of the dynamic stress state in soil under seismic wave propagation. The next drawback of the dynamic theory is an inaccurate, approximate accounting for the displacement of the soil medium to which the underground pipeline is embedded. The complete interaction process includes the stages of nonlinear changes in the interaction force (the friction force) by manifesting its peak value and the Coulomb friction. The contact layer of soil undergoes shear deformations until complete structural destruction of the soil contact layer. The interaction force is the friction force, and its peak value does not appear. The seismic resistance of underground pipelines should be considered based on the theory of propagating seismic waves in a soil medium and the interaction of seismic waves with underground pipelines, i.e., based on the wave theory of seismic resistance of underground pipelines. A one-dimensional coupled problem of seismic resistance of underground pipelines under seismic impacts was posed based on the wave theory. An algorithm and a program for the numerical solution of the stated wave problems were developed using the method of characteristics and the method of finite differences. An analysis of the laws of interaction of underground pipelines with soil under seismic influences shows that it is necessary to use in the calculations the laws of interaction that account for the complete interaction processes observed in experiments. The analysis of the obtained numerical solutions and the posed coupled problems of the wave theory of seismic resistance of underground pipelines show the occurrence mechanisms of longitudinal stresses in underground pipelines under seismic influences. The results of calculations stated that an account for the dynamic stress normal to the underground pipeline's outer surface leads to multiple increases in longitudinal stress in the underground pipeline. This multiple increase is due to the transformation of the interaction force into an active frictional force, resulting from a greater strain in soil than the one in the underground pipeline. Based on the analysis results, a theory of the seismic wave propagation process in an underground pipeline and surrounding soil was proposed. [ABSTRACT FROM AUTHOR]

High-precision detection of the underground pipelines is an indispensable part of the development and construction of cities. At present, the inversion technology for ground-penetrating radar (GPR) data is an effective means of realizing shallow-underground-space visualization in the field of geophysical exploration. However, the traditional full-waveform inversion (FWI) method usually faces the problems of strong nonlinearity of the objective function, high dependence on the initial model, and huge calculation cost. For improving the accuracy and efficiency of GPR data inversion, a wavefield reconstruction inversion (WRI) strategy is used for GPR data imaging to reduce the nonlinearity of the inversion problem and the dependence on the initial model. Then, the frequency weighting strategy and the multi-scale method are adopted to avoid the high-frequency component data dominating the optimization process and enhance the stability of inversion. In this paper, two numerical experiments of pipeline models with different materials and spacing or buried depths verified that the proposed method can effectively reconstruct the subsurface pipelines, and further performance of our algorithm on the field data verified the reliability of high-precision imaging of urban underground pipelines, which shows great potential of application in the field of high-precision detection of the urban underground pipelines.

The ground penetrating radar was applied to the detection of underground pipeline. The signal of ground penetrating radar was analyzed to simulate the different sizes of pipelines and oil. The data were processed by GRED HD software. Radar profiles and single-channel waveforms of underground pipelines and oil were obtained. The nonstationary signals of geological radars were processed and analyzed by the finite-difference time-domain method. The different radar characteristic signals of underground pipelines and radar signal variations of pipeline oil were discussed. It can improve the accuracy of interpretation of underground pipelines and oil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhengzhou University: Engineering Science is the property of Editorial Office of Journal of Zhengzhou University: Engineering Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Collision detection of urban underground pipelines is very significant for pipeline design, pipeline detection and urban safety. Aiming at the problems of low accuracy, inefficiency and dependence on existing commercial platforms in current collision detection algorithms for urban underground pipelines, an efficient and precise collision detection algorithm for underground pipelines is proposed, which is based on projection along common perpendicular. The algorithm classifies the three - dimensional spatial relationship between two pipe segments into two categories including coplanar and heterogeneous. When the central lines of two pipe segments are parallel, collinear or intersectant, whether they collide with each other can be easily judged through the geometric relationship of their center lines and radius size; if the central lines of pipe segments are in different planes, the projection transformation is carried out along the direction of the common perpendicular line first to reduce the spatial dimension, and then the minimum surface clearance between them is obtained through computing the maximum distance between circle and ellipse. Based on the computation above, our proposed algorithm can easily realize precise collision detection for pipelines. Experimental results show that the algorithm not only has high collision detection accuracy for three-dimensional spatial pipelines, but also has good computational efficiency. [ABSTRACT FROM AUTHOR]

Underground pipeline networks constitute a major component of urban infrastructure, and thus, it is imperative to have an efficient mechanism to manage them. This study introduces a secondary development system to efficiently model underground pipeline networks, using the building information modeling (BIM)-based software Revit. The system comprises separate pipe point and tubulation models. Using a Revit application programming interface (API), the spatial position and attribute data of the pipe points are extracted from a pipeline database, and the corresponding tubulation data are extracted from a tubulation database. Using the Family class in Revit API, the cluster in the self-built library of pipe point is inserted into the spatial location and the attribute data is added; in the same way, all pipeline instances in the pipeline system are created. The extension and localization of the model accelerated the modeling speed. The system was then used in a real construction project. The expansion of the model database and rapid modeling made the application of BIM technology in three-dimensional visualization of underground pipeline networks more convenient. Furthermore, it has applications in pipeline engineering construction and management. [ABSTRACT FROM AUTHOR]

The induced voltage on underground pipelines is a critical parameter to consider for equipment and personnel safety in the field. However, in the real life, such induced voltage estimation on pipelines is difficult especially at the transmission line planning and routing stage. In this article, several factors affecting the induced voltage on underground pipelines due to inductive coupling with nearby transmission lines are investigated. These factors include the angle and separation distance between transmission lines and pipelines, the length of transmission lines and pipelines, and the soil model. A peak induced voltage calculation formula as the function of the angle and separation distance is derived through surface fitting of simulation data. It is proved in the article that other factors, such as the length of the transmission line and the soil model types, do not have significant influence on the peak induced voltage values on underground pipelines. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the non-conductive and non-magnetic properties, nonmetallic pipelines are difficult to be detected by traditional pipe location technologies. This paper presents a superimposed imaging method of acoustic wave reflections for pipe location, which operates on the propagation of elastic waves. The propagation and attenuation model of elastic waves in soil are constructed according to the geometric relationship between the acoustic source, geophone array and pipelines. The two-dimensional and three-dimensional acoustic field diagrams of underground pipeline are generated by superimposed imaging of the cross-correlation coefficients between the signals from the sound source and geophone array, with the attenuation caused by hysteretic damping and geometric dissipation considered in the imaging process. In order to suppress clutter interference on the imaging results, the strategy of 'multi-point transmit, multi-point receive and cross-correlation coefficient superposition' is adopted. In the simulation, comparison is made to demonstrate the influences of different excitation sources on the detection imaging results, including the single frequency signal, multi-frequency signal, Gaussian pulse signal and sweep signal. It is found that the excitation signals with rich frequency components are more conducive to improving the resolution of detection images. The effectiveness of the proposed imaging method is further verified in the experimental work, which may be beneficial for the visualization and determination of the location, depth and orientation of underground non-metallic pipelines. [ABSTRACT FROM AUTHOR]