The stable and safe operation of high-speed railways relies on scientific and rigorous maintenance operations.
This article expounds on the specific methods and key points of high-speed rail maintenance from five critical aspects: rail leveling, rail aligning, rail modification, rail grinding, and anti-corrosion treatment for bridge equipment.
I. Rail Leveling
Rail leveling is a crucial process for the comprehensive repair of rail defects. Prior to commencing work, meticulous inspection and comprehensive analysis must be conducted to formulate a scientifically sound repair plan.
Detailed Inspection:
- Based on the rail condition, use the observation posts of the rail precision control network to measure the vertical deviation (actual or design elevation) of the standard rail.
- Within the station numbers where the vertical measurement is taken, use a 50-meter chord to measure the elevation difference between two vertical points of the standard rail.
- For each sleeper, measure the horizontal deviation between the tops of the two rails.
- Additionally, observe the number of empty clips on the sleepers under dynamic conditions, inspect the compaction of the ballast and the consolidation state of the railbed, and examine the condition of the under-sleeper elevation pads. Detailed records should be maintained throughout.
Comprehensive Analysis:
Comprehensive analysis includes both dynamic and static analyses.
- Dynamic Analysis:Utilize the rail inspection vehicle’s amplitude detection to analyze rail defects. Based on the detected amplitudes, identify the specific locations and causes of defects, thereby facilitating the formulation of remedial measures.
- When the inspection vehicle indicates vertical irregularities, factors such as differences in high-low levels along the rail, horizontal deviations, and inadequate tamping are analyzed.
- When horizontal irregularities are detected, factors such as changes in rail alignment and gauge variation rates are considered.
- For composite irregularities, examine periodic occurrences of three or more successive irregularities.
- For other irregularities, consider factors such as variations in vehicle speed and inconsistent elasticity between new and old rails.
- Static Analysis:Conduct this analysis based on actual field survey data. Combine the survey results with the rail inspection vehicle’s diagram analysis to comprehensively identify the causes of defects, focus on key issues, and adopt effective remedial measures.
Formulation of the Repair Plan:
Based on the investigation of rail condition data and the comprehensive analysis of defect causes, appropriate remedial measures are formulated. Key points include:
- “Use underlayment as the primary measure, combine tamping with underlayment; first eliminate empty clips using sleeper pads; remove adjustment boards during rail leveling; ensure proper pad thickness; perform secure tamping; apply the correct amount of leveling without over- or under-correction; and rely on accurate data to achieve rail smoothness.
- Ensure that the railbed has proper drainage, is free from contamination, and maintains its dimensions.
- For switches, prioritize tamping over rail leveling—do not overuse sleeper pads, and if used, remove them promptly.”
II. Rail Aligning
Rail aligning is essential for ensuring the accuracy of rail alignment. Before commencing work, secure any loose bolts and consider climatic variations.
For Straight Sections:
- Based on the alignment condition of the straight rail, measure the standard rail gauge to establish alignment reference points.
- Use a 50-meter chord to measure the alignment deviation between two gauge points.
- Based on the data variations, eliminate deviations and continuous small S-shaped irregularities, and remove variations in curvature.
For Curved Sections:
- Based on the alignment condition of the curved rail, measure the standard rail gauge to establish alignment reference points.
- Over the entire curve, use a fixed chord length to detect the change rate of the deflection (ordinate) curvature at 1-meter intervals on each side. In the transition curve, measure the incremental change in the deflection ordinate.
- Based on the changes in gauge and the data from the deflection curvature and its incremental change, adjust the curve profile and the transition between straight sections and the ZH/HZ points appropriately to mitigate oscillations as trains enter or exit the curve.
- After aligning, allow the train wheels to run over the rail before securing the anchoring posts.
For High-Speed Switches:
- Understand the alignment variation patterns specific to high-speed switches.
- Observe the alignment changes before and after temperature fluctuations; measure and analyze gauge variations to identify key alignment areas; and reinforce these key areas accordingly.
- Depending on the directional changes between up and down lines, between switches, or between switches and the mainline, perform joint alignment to ensure the rail’s stability.
III. Rail Modification
Rail modification aims to correct issues with rail alignment and gauge, ensuring that the geometric dimensions of the rail system meet the standards.
Data Measurement and Analysis:
- Based on the alignment condition of the straight rail, measure the standard rail gauge deviation data.
- Use a 50-meter chord to measure the alignment deviation between two gauge points.
- For each sleeper, measure the gauge deviation between the two rails.
- Analyze these survey data to identify the causes of defects and establish a rail modification plan.
Implementation of Rail Modification:
- Follow the established modification plan and procedures to correct minor alignment deviations, gauge irregularities, and variations in gauge rate.
- Ensure that the fasteners are maintained in a condition described as “complete, properly positioned, tight, adequately lubricated, and securely fastened,” thereby eliminating gaps between the nylon pads and the sleeper abutments, between the clips and the nylon pads, and between the rail bottom and the clips.
- Conduct re-inspections promptly after the work is completed.
IV. Rail Grinding
Rail grinding is a key maintenance activity in high-speed rail upkeep, and the quality of grinding directly affects the rail’s smoothness and straightness. In China, rail grinding is classified into three categories: corrective (repair) grinding, maintenance (profile) grinding, and preventive grinding.
Corrective Grinding:
- Focus on eliminating irregularities and misalignments at rail welds, rectifying wavy patterns on the rail head, promptly welding and repairing rail defects, and grinding off any flash from the rail, tip, web, base, and center sections.
- This process enhances the continuous smoothness of the rail and reduces deductions during rail inspections.
- It can also address inherent design irregularities in the rail web and tip.
Maintenance and Preventive Grinding:
- Conduct grinding operations periodically using rail grinding machines to perform routine maintenance and remedial work, thereby extending the service life of the rail.
A technician pushing a rail grinding machine forward
V. Anti-Corrosion Treatment for Bridge Equipment
Anti-corrosion treatment is a critical component in ensuring the quality of bridge equipment. Equipment corrosion not only complicates maintenance and repairs but may also result in significant losses to national assets.
Scope of Anti-Corrosion Work:
The anti-corrosion treatment for bridge equipment covers not only the corrosion protection of bolts but also includes various connecting components and rail elements.
Implementation of Anti-Corrosion Measures:
Regularly apply oil to the relevant equipment, monitor the corrosion status, and increase the frequency of oiling in sections where severe corrosion is observed to ensure that the equipment remains rust-free.
Conclusion:
By implementing these systematic and comprehensive maintenance methods, the safe and stable operation of high-speed railways can be effectively ensured, providing a solid foundation for the high-speed and smooth operation of trains.
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