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Research on the Zoning Scheme of Active Fault Influence and Route Selection in Railway Engineering

LUO Feng, DU Shihui, XIA Mingxiao, CHEN Xingqiang, ZHENG Liangliang, DING Zihao

Journal of Railway Engineering Society. 2026, 43(4): 1-6.

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Research purposes: Active faults are increasingly impacting railway route selection in western China and neighboring regions. In particular, the broad, gentle river valleys formed by the subsidence of large active faults are usually densely populated economic strongholds, making it unavoidable for railway lines to pass through areas with active fault development. After an active fault triggers an earthquake, it often affects the safety of railway operations in the form of direct fault displacement or secondary geological disasters. Therefore, an active fault impact zoning scheme for railway engineering is proposed to effectively guide route selection in the active fault development area and mitigate the engineering geological risks of active fault at the source.
Research conclusions: (1) Based on the modes of engineering damage caused by active faults, the active fault impact zone is divided into fault dislocation influence zone and earthquake ground motion influence zone. An active fault impact zoning scheme for railway engineering is proposed, with the primary classification distances from Holocene active faults set at 0.2 km or 0.4 km (0.2 km for seismic fortification intensity zones of 8 degrees and 0.4 km for seismic fortification intensity zones of 9 degrees), 1 km, 3 km, 5 km, and 10 km. (2) The geometric distribution and activity characteristics of four Holocene active faults along the China-Kyrgyzstan-Uzbekistan Railway (Kyrgyzstan section) were determined in detail through remote sensing, trenching, and field mapping. Geological route selection was then conducted based on the proposed zoning scheme. An analysis of active fault impacts on the railway engineering indicated that the CK scheme was superior to other alternatives and was adopted as the construction scheme. (3) This research findings can effectively guide the active fault avoidance, geological survey and route selection for railways, highways and other transportation projects in areas with active fault development.

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Study on the Main Technical Standards of Freight Railway in East Kalimantan of Indonesia

ZHOU Chenghan

Journal of Railway Engineering Society. 2026, 43(4): 7-11.

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Research purposes: As a prerequisite for determining railway alignment, transportation organization modes, main engineering measures and project costs, the establishment of main technical standards is critical during preliminary research. These standards directly influence the project's investment benefits and operational efficiency. Specifically, axle load, train formation schemes, and gradient limitations serve as foundational parameters for selecting traction types, determining hauling capacity, and specifying locomotive and rolling stock requirements. These factors represent the core technical standards for heavy haul railways and are key to research on freight railway technical specifications.
Research conclusions: (1)Chinese heavy-haul railway technology is well-aligned with Indonesia's bulk cargo transportation needs and development context, offering advantages in compatibility, cost-effectiveness, feasibility, and local integration.(2) The comparison and selection of axle load and train formation schemes should comprehensively consider factors such as locomotive and rolling stock performance, engineering costs, and operational expenses. Gradient limitations should be analyzed in terms of traffic characteristics, terrain conditions, traction and braking performance, and project cost implications. (3)Following comprehensive evaluation, the recommended main technical standards include an axle load of 30 t, a train formation of "3 locomotives + 116 mining wagons", and gradient limitations of 8‰ for loaded train direction and 15‰ for empty train direction, ensuring low engineering investment, high operational efficiency, and favorable economic returns. (4)The research methodologies and analytical frameworks proposed in this paper can serve as references for the selection of main technical standards in similar overseas mining railway projects.

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Research on Intelligent Grading Model of Surrounding Rock Based on FT-Transformer + SupCon

JIA Zheqiang, WANG Dong, ZHANG Ru, XU Zhengxuan, SUN Junlong, ZHANG Anlin

Journal of Railway Engineering Society. 2026, 43(4): 12-17.

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Research purposes: Surrounding rock classification is critical to the design, construction, and risk control of tunnels and underground engineering, and its criteria are directly related to safety redundancy and investment efficiency. In practice, field data often consists of descriptive features in Chinese, while existing studies typically quantify and weight these features, resulting in challenges such as semantic loss, subjective weighting, difficulty in characterizing high-order interactions, and unstable discrimination under imbalanced data. Therefore, this article proposes an intelligent classification prediction method for surrounding rock based on Chinese descriptive features in geological records.
Research conclusions: (1) A surrounding rock classification model based on FT-Transformer with supervised contrastive learning (SupCon) is proposed, by modeling Chinese category features using column and field embedding, utilizing multi-head self-attention to obtain cross-column dependencies, and jointly optimizing with cross-entropy and SupCon to enhance intra-class cohesion and inter-class separation. (2) Trained and validated on 1169 samples from a deep buried tunnel in a railway project in western Sichuan, the model achieves an overall accuracy of 94.9%, with good generalization and engineering consistency. (3) The research results can provide reference for the rapid and accurate classification of surrounding rock in deep buried tunnels.

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Analysis of In-situ Stress and Rockburst Risk in a Plateau Tunnel

MENG Shaowei, XU Zhengxuan, WANG Zhewei, FENG Junjie, YUAN Dong, CHEN Yu

Journal of Railway Engineering Society. 2026, 43(4): 18-22.

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Research purposes: The Hengduan Mountains in China features complex geological structures, and the in-situ stress field exhibits high magnitude and strong anisotropy. The construction of deep-buried tunnels in this area faces severe rockburst risks. This study, based on an extra-long deep-buried tunnel project in southwestern China, employed the hydraulic fracturing method to conduct in-situ stress measurements along the tunnel route. A two-dimensional finite element model of the tunnel's longitudinal profile was established to inversely analyze the distribution characteristics of the maximum principal stress along the tunnel axis. The study systematically examines the distribution patterns of in-situ stress and their intrinsic relationship with rockburst risk.
Research conclusions: (1) The in-situ stress state in the tunnel area shows a significant linear positive correlation with burial depth (R² > 0.78). When the burial depth exceeds 600 m, the in-situ stress structure manifests as a strike-slip type (S_H > S_v > S_h). The lateral pressure coefficient (λ) gradually approaches 1 with increasing depth, indicating a weakening of horizontal tectonic influence. (2) Inversion analysis of the in-situ stress indicates noticeable stress release within fault zones, while stress concentration is observed in the intact rock masses. (3) The strength-stress ratio method of surrounding rock reveals that the section from DK0+537 to DK15 is primarily prone to slight rockbursts, whereas the section from DK15 to DK27 carries a moderate rockburst risk. Specifically, locations at DK16, DK21, and DK24 are identified as having higher risk. (4) This research provides a scientific basis for rockburst early warning and support design during tunnel construction, offering significant guidance for ensuring the safe construction of deep-buried tunnel projects under similar geological conditions.

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Research on Planar Parameters for Alignment Fitting of Long Straight Sections in Operational Railways

ZHANG Wei

Journal of Railway Engineering Society. 2026, 43(4): 23-27.

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Research purposes: During long-term operation, railway lines are influenced by factors such as surveying and construction errors, repeated loading, and geological changes, therefore, long straight sections cannot always maintain a standard straight alignment. Instead, they may develop small deflection angles at intervals, forming several small-deflection-angle segmented alignments. In railway maintenance, especially for ballastless track sections, sensitivity to line deviation values is high. Whether long straight sections can be fitted as segmented alignments with small deflection angles and the rationality of fitting parameters directly affect train operational safety, passenger ride comfort, and the scale of reconstruction work. Currently, research on the alignment fitting of straight sections decomposed into segmented alignments with small deflection angles is scarce, and existing standards lack relevant explanations and guidance. This leaves on-site maintenance work without a scientific basis, often leading to issues such as unreasonable fitting parameter selection and suboptimal maintenance outcomes. This paper focuses on a 200 km/h railway. By establishing a vehicle-track dynamics model and employing dynamic simulation analysis, it explores the minimum reasonable length for segmented alignments when decomposing long straight sections and identifies the maximum deflection angle threshold that can still be regarded as a standard straight line from the perspectives of train operational safety and passenger ride comfort. The findings aim to provide a reference for fitting methods and on-site maintenance work of existing railway straight sections.
Research conclusions: (1) At a design speed of 200 km/h, when the deflection angle of small-deflection-angle segmented alignments is ≤4′, its impact on vehicle dynamic responses is negligible, and such segments can be considered as standard straight lines. (2) The length of the segmented line primarily influences the attenuation of the train's dynamic response. When the train travels 400 m past the deflection point, peak values of various dynamic indicators attenuate by more than 90%; at 600 m, attenuation is essentially complete. Therefore, under general conditions, the minimum length of the segmented line is recommended to be 600 m, while under constrained conditions, 400 m can be adopted. (3) The findings of this study can provide guidance and a theoretical basis for the alignment fitting design during the maintenance phase of existing 200 km/h railways.

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Study on the Elastic Support Composite Short Sleeper Track Type and Its Simulation Effectiveness

LI Yi, PAN Zili, YANG Junbin, LIU Tao, LI Baoyou

Journal of Railway Engineering Society. 2026, 43(4): 28-33.

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Research purposes: The adaptability to foundation deformation is a critical focus in current research on structural types of ballastless track.This paper proposes a novel ballastless track structure with elastic-support composite short sleepers for areas susceptible to foundation deformation. A three-dimensional numerical model of this track structure was established, and its accuracy was verified through laboratory-scale model tests. Based on the deformation wavelength, load type and magnitude determined from relevant studies, various calculation scenarios reflecting actual foundation deformation characteristics were formulated. The vertical and lateral displacements of each structural component under these different scenarios were computed using the developed numerical model. The adaptability of the track structure to different foundation deformations was analyzed by comparing the displacements of the sleeper and track slab across scenarios, and by evaluating the rail displacement against the allowable deviation limits specified in maintenance regulations for track geometry. Furthermore, the intrinsic dynamic characteristics of the structure were investigated by analyzing its multi-order natural frequencies.
Research conclusions: (1) When the foundation deformation wavelength does not exceed 5 m, both the vertical and lateral deformations of the track structure comply with the allowable limits specified in the current maintenance code. However, when the foundation deformation wavelength exceeds 5 m, the vertical displacement of the track structure exceeds the code requirements. (2) Between lateral and vertical displacements, the vertical displacement alone can serve as the indicator for evaluating the track structure's adaptability to foundation deformation. (3) In the first three vibration modes, the vibration resistance of the track structure designed in this paper shows no significant degradation. (4) The research findings provide a reference for the study of track structures in active fault zones and high-stress areas.

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Study on the Correlation Mechanism Between Deck Geometry and Temperature in Long-span Steel Truss Arch Bridges

YANG Guojing, HE Tingguo, WU Tao

Journal of Railway Engineering Society. 2026, 43(4): 34-39.

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Research purposes: The mountainous terrain in western regions is complex, with pronounced diurnal and seasonal temperature variations. Large-span railway steel truss arch bridges are prone to developing non-uniform temperature fields due to mountain shading and variations in deck coverage, which significantly affect structural stress states and deck geometry. This study, based on the real-time data from the health monitoring system of the Nujiang Bridge on the Dali-Ruili Railway, employs regression analysis to systematically investigate the temperature distribution characteristics under large temperature differentials and their influence on deck geometry.
Research conclusions: (1) The long-term evolution of deck geometry is significantly positively correlated with the average daily temperature: at low temperatures, the bridge deck sags into a "V" shape; at high temperatures, it arches and transitions to a "W" shape, with the symmetry center deviating from the arch crown and shifting to the right. (2) The temperature of each part of the structure is significantly affected by shading effects. The maximum temperature differences between the ambient temperature and the upper/lower chords at the arch crown, as well as the lower chord at the arch foot, are 9.3 ℃ and 10 ℃, respectively. The structural temperature response lags ambient temperature by 2-4 hours. The measurement point at the 3/4 section of the 3rd arch rib exhibits the smallest mean temperature deviation from the ambient temperature (1.82 ℃). (3) The single measurement point temperature mode has limitations such as incomplete representation and time deviation. Among multiple measurement points, the combination of "arch crown arch rib + average temperature of main girder web" has the best fitting effect. The constructed regression function y=7.125 9x+1.652 6 can quantitatively describe the changes in the bridge deck geometry. (4) The research results can provide theoretical support for temperature effect analysis and structural performance evaluation of similar bridges.

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Research on Stiffness Improvement Method of Single Tower Swivel Cable-stayed Bridge

SONG Yufeng

Journal of Railway Engineering Society. 2026, 43(4): 40-44.

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Research purposes: In recent years, with the increasing demand for construction across railways, the application of large-span single tower swivel cable-stayed bridges has gradually increased. At present, most completed or under-construction single tower swivel cable-stayed bridges adopt a symmetric layout system without auxiliary piers or auxiliary spans, offering no advantages in overall structural stiffness. A small number of single tower swivel cable-stayed bridges are equipped with auxiliary piers or adopt an asymmetric span layout. Taking a certain single-pylon swivel cable-stayed bridge as an example, this paper takes increasing pylon stiffness, installing auxiliary piers, setting cooperative spans and adopting asymmetric spans as variables to analyze and compare the influence of different measures on the overall stiffness of the bridge.
Research conclusions: (1) With the main span fixed, increasing the pylon stiffness, installing auxiliary piers, setting cooperative spans and adopting an asymmetric span layout can all improve the overall stiffness of the bridge. (2) Installing auxiliary piers and setting cooperative spans have a significant effect on enhancing the overall stiffness of single tower swivel cable-stayed bridges, while increasing the pylon stiffness exerts a limited influence on improving the overall bridge stiffness. (3) The position and number of auxiliary piers are correlated with the main span length, and different proportional relationships between the cooperative span and the main span exert a certain impact on the overall bridge stiffness. (4) The structural system with auxiliary piers and cooperative spans has been common in the design of conventional cable-stayed bridges, yet relevant research and application are scarce in the design of swivel cable-stayed bridges. The research has innovative and practical value,providing effective stiffness improvement schemes and optimal design strategies for the design of long-span single-pylon swivel cable-stayed bridges in the future.

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Analysis of Influence Parameters and Limit Values for the Resultant Force Eccentricity of Railway Bridge Piers

JIANG Chengqiang

Journal of Railway Engineering Society. 2026, 43(4): 45-52.

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Research purposes: When performing eccentricity checks on low-reinforcement gravity piers of railway bridges under frequent earthquakes, the influence of reinforcement can be appropriately considered to increase the resultant force eccentricity. To explore the influence mechanism of various factors on the resultant force eccentricity of low-reinforcement gravity piers of railway bridges, this study systematically summarizes the main influencing factors and conducts parameter analysis. Through theoretical analysis, the calculation formulas and limit values for the resultant force eccentricity of different types of piers are derived.
Research conclusions: (1) For piers without a slope, the resultant force eccentricity is mainly influenced by pier height and reinforcement ratio. For piers with a slope, the resultant force eccentricity is only related to the reinforcement ratio, and each parameter has a linear relationship with the resultant force eccentricity coefficient. (2) The calculation formulas and limit values for the resultant force eccentricity coefficient of bridge piers with and without slope under different design speeds were proposed. The resultant force eccentricity coefficients calculated by the formulas are basically consistent with those calculated by the allowable stress method, with maximum error of 1.59% for pier with a slope and 2.52% for pier without a slope. (3) The maximum allowable resultant force eccentricity coefficients for different types of bridge piers under various speeds are provided when the longitudinal reinforcement is HRB400, and the calculation method for the maximum allowable resultant force eccentricity coefficient when using HRB500 longitudinal reinforcement is determined. (4) The research results provide a theoretical basis for the seismic design of railway gravity bridge piers under frequent earthquakes.

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Digital Twin-driven Optimization Method for Railway Bridge Construction Organization

LIU Yanming, ZHU Qing, DING Yulin, MIAO Wenhui, HUANG Ting

Journal of Railway Engineering Society. 2026, 43(4): 53-58.

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Research purposes: Railway bridge projects involve numerous elements with complex relationships, consisting of multiple interrelated construction processes and being constrained by various resource types such as labor, machinery, and equipment. Existing railway bridge construction organization mainly relies on the experience of compilers, resulting in a long compilation cycle and inability to adapt dynamically to site changes, making it difficult to find the optimal solution under multi-mode resource-constrained conditions. This paper integrates digital twin technology with an improved Discrete Particle Swarm Optimization (DPSO) algorithm to construct a digital twin model for railway bridge construction organization optimization, and verifies its accuracy and superiority using data from a typical bridge project.
Research conclusions: (1) The proposed method—integrating digital twin with DPSO algorithm—can effectively address the challenges of formulating and dynamically optimizing multi-mode resource-constrained construction organization in railway bridge projects. (2) The proposed DPSO algorithm is significantly superior to the three benchmark algorithms in terms of cost control, reducing the average total cost by 17.23% under different activity scales and maximum duration settings. (3) Experimental verification in practical railway bridge projects demonstrates that the program compiled based on this optimization method can rapidly generate construction organization schemes, significantly improving both efficiency and quality. This makes it suitable for widespread application in the formulation and optimization of construction organization for railway bridges.

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Research on Mechanized Construction Issues of Deep-buried Central Drainage Ditches in Cold-region Tunnels

LI Guoliang, CAO Guodong, DAI Zhiren, QI Zhanfeng, GUO Limin, XU Dengfei

Journal of Railway Engineering Society. 2026, 43(4): 59-64.

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Research purposes: The deep-buried central drainage ditch in cold-region tunnels is a critical frost-proof drainage structure that ensures tunnel stability and operational safety. Traditional construction methods suffer from low efficiency, insufficient mechanization, and significant interference with main tunnel excavation. With the increasing scale of cold-region tunnel projects and the widespread adoption of TBM methods, the conventional manual drilling-and-blasting approach can no longer meet the demands of efficient and coordinated modern tunnel construction. This paper systematically investigates mechanized construction technologies for deep-buried central drainage ditches in both drill-and-blast and TBM tunnels. It proposes multiple targeted construction schemes to address technical challenges, including schedule mismatches and construction interference between ditch and main tunnel works, thereby providing theoretical support and practical pathways for high-quality construction in cold-region tunnels.
Research conclusions: (1) The design of deep-buried central drainage ditches should adhere to the "whole-tunnel frost prevention" principle, prioritizing externally drained and fully connected layouts to enhance system reliability and durability. (2) For construction and maintenance convenience, inspection shafts for deep-buried central drainage ditches should preferably be located in the middle of the tunnel. (3) The four construction schemes proposed in this study cover different ground conditions ranging from hard rock to soft soil. Among them, the integrated trestle-drilling rig offers advantages such as high integration and compact working space, representing the technological development direction in this field. (4) Synchronized mechanized construction of deep-buried central drainage ditches is achievable in TBM tunnels. (5) The pipe jacking scheme and the "track slab + invert trestle" scheme are suited to different construction environments, effectively resolving mechanized construction challenges for deep-buried central drainage ditches in TBM tunnels and filling a technical gap in this field.

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Research on the Eccentric Compression Performance of Composite Structure Segments in Large-span Tunnels

GUO Liang

Journal of Railway Engineering Society. 2026, 43(4): 65-71.

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Research purposes: At present, reinforced concrete segments are widely used in lining structures of large-diameter tunnels and metro stations. However, they have problems such as large self-weight, high concrete consumption, insufficient crack resistance, and low construction and assembly efficiency, which make it difficult to meet the requirements of lightweight and high bearing capacity under complex geological conditions. To solve the above problems, this paper proposes a hollow steel-concrete composite segment, and carries out an eccentric compression static loading test on a large-diameter hollow steel-concrete composite segment. Based on the experimental study, the refined numerical simulation method for large-diameter hollow steel-concrete composite segments using finite element software was verified. Furthermore, a comprehensive parametric response analysis was conducted on factors such as hollow steel pipe size, wall thickness, eccentricity ratio, and concrete strength grade.
Research conclusions: (1) During eccentric compression loading, the overall stress behavior of hollow steel-concrete composite segments exhibits distinct phased evolution characteristics. As the load increases, the lateral deformation of the component gradually transitions from linear to nonlinear growth, ultimately entering a stage of capacity degradation. (2) The finite element model effectively replicates the overall deformation and failure process of the specimen. During the elastic stage, the predicted stiffness and peak load-bearing capacity show deviations of 6.4% and 2.6%, respectively, meeting engineering accuracy requirements. (3) The extended parametric analysis indicates that the peak load-bearing capacity first increases and then decreases with increasing hollow steel pipe size, whereas it increases with greater wall thickness. Higher eccentricity results in a reduction of peak capacity accompanied by a pronounced increase in mid-span deflection. In addition, a higher concrete strength grade enhances the ultimate load-bearing capacity under eccentric compression and improves deformation resistance throughout the initial and subsequent loading process. (4) This achievement can be applied to the field of lining structure design for large-span tunnels and underground engineering.

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Dynamic Simulation and Evolution Characteristics of High-speed Railway Catenary Icing

HE Changhong, LI Zheng, LIU Jidong, WU Mengzhen, ZHENG Jun, LI Shaopeng

Journal of Railway Engineering Society. 2026, 43(4): 72-78.

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Research purposes: As the operating mileage and running speeds of high-speed railways in China continue to increase, a growing proportion of lines are operating in complex climatic regions characterized by low temperatures, high humidity, and strong winds, making atmospheric icing of the catenary increasingly prominent. Icing significantly alters the geometric morphology and electrical properties of the pantograph-catenary contact interface, which may lead to unstable current collection and frequent arcing. In severe cases, it can cause train service interruptions and delays, and has become a critical environmental factor restricting the safe operation of high-speed railways. In view of the insufficient understanding of the icing formation mechanism and the unclear dynamic evolution characteristics of catenary icing, this study systematically investigates the icing formation and growth process, establishes a dynamic evolution analysis method for catenary icing, and provides theoretical support for the safe operation of catenary under complex climatic conditions.
Research conclusions: (1) A dynamic icing evolution model for the catenary is established by coupling airflow computation with ice profile growth analysis. Using collision efficiency, capture efficiency, and freezing fraction as key parameters, the model enables quantitative characterization of the temporal evolution of ice thickness and profile morphology. (2) The influences of meteorological factors, including ambient temperature, wind speed, and liquid water content, on icing growth rate and spatial distribution characteristics are clarified, and the stage-dependent differences in icing development under various parameter combinations are identified. (3) A state-tracking algorithm is introduced to continuously identify and quantitatively classify the icing development process, achieving dynamic characterization from initial adhesion to the stable growth stage. (4) The research findings can be applied to icing prediction and assessment, operational risk warning, and the optimization design of anti-icing and de-icing technologies for high-speed railway catenary under complex service climatic environments.

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Pantograph-catenary Dynamic Performance Evaluation of Existing High-speed Railway Running at 400 km/h

ZHANG Kai, YANG Jia, YU Jie, WANG Chao, GUAN Jinfa

Journal of Railway Engineering Society. 2026, 43(4): 79-83.

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Research purposes: As China's high-speed railways continue to aim for higher operational speeds, whether existing lines designed for 350 km/h can adapt to future operational requirements of 400 km/h has become a critical issue affecting railway speed enhancement and operational safety. Addressing this practical need, this paper focuses on an in-depth study of the pantograph‑catenary system—the core coupled unit of high‑speed railways. By establishing five different types of dynamic simulation models for existing pantograph‑catenary systems operating at 350 km/h, we systematically simulate and analyze the evolution patterns of the dynamic performance of these existing systems under elevated train speeds of 400 km/h. From a dynamics perspective, the adaptability, stability, and reliability of the current system under higher‑speed conditions are thoroughly evaluated.
Research conclusions: (1) With the speed increased to 400 km/h, the pantograph-catenary dynamic interaction intensifies significantly, with certain indicators approaching or exceeding established safety thresholds. (2) The dual-pantograph dynamic performance indicators on the Beijing-Guangzhou and Beijing-Shanghai high-speed railway pilot sections, as well as the single-pantograph dynamic performance indicators on five existing 350 km/h high-speed railways, all meet the standard requirements. (3) For the Beijing-Shanghai and Shanghai-Hangzhou high-speed railways, modifications are needed—specifically through retrofitting the catenary overlap sections and mid-anchor sections, respectively—to enhance dual-pantograph dynamic performance before they can comply with the standard. (4) As the speed of existing high-speed railways is increased to 400 km/h, both dual-pantograph and single-pantograph operations exhibit a significant increase in catenary vibration amplitude and frequency. Further verification is required to determine whether the current catenary system and component conditions, along with their service life, can accommodate these increased demands. (5) This study provides a theoretical basis and technical support for the speed increase retrofitting of high-speed railways.

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Adaptive Robust Control of Pantographs Considering Actuator Performance Degradation

CHEN Chen, CHEN Wei, WEI Jianzhong

Journal of Railway Engineering Society. 2026, 43(4): 84-89.

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Research purposes: The stable contact of the pantograph-catenary (pan-cat) system is crucial for ensuring the safe and reliable current collection of trains. Engineering practice shows that after long-term high-speed operation, pantograph actuators suffer from performance degradation due to factors such as aging and wear, leading to decreased control precision and deviations in responding to control commands. This non-ideal operating condition degrades the dynamic contact performance of the pan-cat system, increases contact force fluctuations, and threatens operational safety. To ensure that the pan-cat system maintains high-quality contact even under actuator performance degradation, this paper develops a robust control method for pantographs that does not rely on an accurate system model and can adaptively compensate for performance loss online, thereby enhancing system reliability.
Research conclusions: (1) To address the problem of actuator performance degradation, a model-free adaptive robust control framework is constructed, which transforms the complex controller design into a time-varying parameter optimization problem and achieves online self-tuning of control gains through an improved cost function. (2) An online estimation and compensation mechanism based on a Radial Basis Function Neural Network (RBFNN) is designed, which can perceive and compensate in real time for the adverse effects of actuator performance degradation, enhancing the adaptive robustness of the system. (3) The uniform boundedness of the neural network weight estimation error and the pan-cat contact force tracking error under the proposed method is theoretically proven, ensuring the stability of the closed-loop system. (4) Simulation results show that under actuator performance degradation, the proposed method reduces the average pan-cat contact force by 49% and 42%, compared to traditional PID and LQR control methods, respectively, and decreases the contact force standard deviation by 52% and 50%, effectively maintaining the stability of the pan-cat contact quality. (5) This research provides an effective solution to the control challenges caused by pantograph actuator performance degradation during long-term service, offering significant support for improving the operational safety of high-speed railways.

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Research on the All-scenario System of Smart Hubs Facing Service Recipients

SUN Yawei

Journal of Railway Engineering Society. 2026, 43(4): 90-93.

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Research purposes: With the increasing and diversifying travel demands of passengers, smart hubs have already become the key to improving service quality and management efficiency.This paper analyzes the current pain points of railway hubs. Based on the two main stakeholder groups—passengers/citizens and managers, it explores smart hubs' subdivision application scenarios,and proposes a full-scenario smart solution to enhance the travel experience of passengers and improve the efficiency of station operation and management.
Research conclusions: (1) The construction of smart hubs should target two key groups: passengers/citizens, aiming to enhance their travel experience, and managers, aiming to improve the efficiency of station operation and management. (2) This paper analyzes smart hubs' subdivision scenarios to propose full-scenario solutions: for passengers and citizens, focusing on multi-domain intelligent sensing for travel, smart passenger services and smart business; for managers, focusing on smart operation, smart maintenance, smart asset management, smart emergency support, and energy & carbon management. (3) This study can provide guidance for the design of smart railway hubs and offer theoretical support for identifying their scenario requirements.

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Research and Application of Intelligent Subgrade Design System

LI Yao, ZHANG Xiechong, YAO Hongxi, XIE Hao, MAO Guocheng

Journal of Railway Engineering Society. 2026, 43(4): 94-99.

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Research purposes: The digital and intelligent upgrading of subgrade engineering design in the land transportation sector is a crucial response to China's major strategies of "Powerful Transportation Country" and "Digital China". However, traditional subgrade design suffers from issues such as low data standardization, reliance on manual decision-making for plans, inefficient parameter optimization, and the separation of 2D and 3D designs. Additionally, there is a risk of being constrained by foreign graphic platforms. Therefore, it is imperative to develop an intelligent subgrade design solution with independent intellectual property rights to accelerate the digital transformation of the transportation industry.
Research conclusions: (1) Digital intelligent design and delivery standards for subgrade engineering are established. A decision-making method integrating knowledge graphs and graph neural networks is proposed. Intelligent parameter optimization technology for subgrade structure is developed based on adaptive hyper-heuristic algorithms. 2D&3D integrated design and linkage update technologies guided by adaptive guide lines are constructed. (2) Based on a platform-decoupled architecture and domestically developed graphic engines, a comprehensive intelligent subgrade design system is developed. This system integrates functions such as collaborative data management, intelligent scheme decision-making, structural parameter optimization, 2D&3D linked design, and automatic result output. (3) The system has been applied in railway and highway subgrade projects, improving overall design efficiency by over 40%. It innovates a new mode for integrated 2D&3D intelligent subgrade design, achieving digitalization, intelligence, and autonomy in subgrade design operations. This advancement promotes technological progress in engineering survey and design within the land transportation sector, and the outcomes can also provide a reference for similar geotechnical engineering designs.

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Research on Shield Tunneling Parameters and Attitude Control in Different Curves

PENG Jun, LIU Fusheng, LIU Keqiang

Journal of Railway Engineering Society. 2026, 43(4): 100-105.

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Research purposes: As a key construction technology for modern subways, shield tunneling plays an important role in improving urban transportation capacity and alleviating traffic pressure. Taking a section of a city's metro line as an example, this paper analyzes the tunneling parameters by mathematical statistics, focuses on the differential impact of curve radius on tunneling parameters in the same stratum, and further proposes measures for shield machine attitude control.
Research conclusions: (1) The increased frictional resistance between rock mass and shield machine in small-radius curve sections leads to greater total thrust and stronger discreteness of the shield machine. (2) In large-radius curve sections, the tunneling speed can be improved by appropriately reducing total thrust and increasing cutterhead torque. (3) During construction, the axis deviations in both horizontal and vertical directions are controlled within 2.00%, indicating good adaptability between tunneling parameters and stratum, but the construction and shield attitude control in small-radius curve sections are more difficult. (4) Reasonable selection of assembly points and appropriate reduction of horizontal thrust can significantly improve the effect of shield attitude control. (5) For small-radius curve tunnels, the sensitivity and correction capability of shield machine can be improved by adjusting its articulation. (6) This study can provide references for the safety of shield tunneling and the rationality of parameter settings.

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Research on Urban Rail Traction Power Supply System Based on Bidirectional Converter Technology

HE Fan

Journal of Railway Engineering Society. 2026, 43(4): 106-110.

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Research purposes: In response to the current issues of high operating energy consumption and power quality problems in urban rail transit traction power supply systems, this paper integrates bidirectional converter control and centralized energy control management technologies. Taking the active traction power supply system of a specific urban rail transit line as the research subject, it compares the operational data of the bidirectional converter unit under three modes—auxiliary traction control, local voltage stabilization control, and online energy operation control—to quantitatively analyze the energy-saving effects and power quality improvement of the traction power supply system under different control strategies, providing empirical evidence and decision-making references for the optimized design and economical operation of traction power supply systems.
Research conclusions: (1) The study demonstrates that the bidirectional converter local voltage stabilization mode achieves an energy-saving rate of 6.4% compared to the traditional auxiliary traction mode, while reducing grid voltage fluctuations by 32.7%. When combined with the energy operation control system, the overall energy-saving rate increases to 6.8%. (2) It validates the comprehensive benefits of bidirectional converter technology in practical engineering projects and provides empirical evidence for energy optimization and stability enhancement in urban rail traction systems.

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15 April 2026, Volume 43 Issue 4

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15 April 2026, Volume 43 Issue 4