周宇 王蒙一 梁旭 姚凯洲

摘要： 【目的】为分析钢轨材质、残余应力、温度应力在钢轨使用中的内外因对轨底裂纹扩展的影响开展研究。【方法】基于断裂力学理论结合轨底伤损实测，建立钢轨轨底裂纹扩展模型，对轨底伤损扩展失效时的临界裂纹尺寸、裂纹平均扩展速率、剩余寿命等指标进行量化分析。【结果】结果表明：钢轨材料断裂韧性与轨底初始伤损扩展的剩余寿命存在正相关关系，U95Cr H材质钢轨的轨底裂纹扩展剩余寿命小于U78CrV H材质小于U75V H材质；以某线路实际使用的钢轨材质U78CrV H为例，轨底残余应力由0增加至300 MPa，轨底裂纹扩展的临界尺寸增长约2.5%，剩余寿命下降约6%；残余应力为200 MPa时，温度应力由0增加至200 MPa，轨底裂纹扩展的临界尺寸变化不大，在1%内。【结论】研究结果可为轨底裂纹扩展研究和养护维修提供参考。

关键词：钢轨；轨底裂纹；裂纹扩展；残余应力；温度应力

中图分类号：U213 文献标志码：A

文章编号：1005-0523（2024）02-0095-07

Analysis of Factors Affecting the Growth of Rail Bottom Cracks

Zhou Yu1，2， Wang Mengyi1，2， Liang Xu3， Yao Kaizhou1，2

（1. Key Laboratory of Road and Traffic Engineering of the Ministry of Education， Tongji University， Shanghai 201804， China；

2. Key Laboratory of Structural Durability and System Safety of Shanghai Rail Transit， Tongji University， Shanghai 201804， China；3. Metals & Chemistry Research Institute， China Academy of Railway Sciences Corporation Limited， Beijing 100081， China）

Abstract： 【Objective】In terms of the rail material， residual stress， temperature stress and other factors， work conditions are respectively designed to explore the influences of rail bottom crack expansion. 【Method】Based on the theory of fracture mechanics， combined with rail bottom measurement， the model of rail bottom crack expansion has been established and indicators such as critical crack size， average crack extension rate as well as remaining life has been quantified. 【Result】It is found that there exists positive correlation between the fracture toughness of rail material and the remaining life. The remaining life of U95Cr H is less than U78CrV H， which is less than U75V H. Taking U78CrV H， used in the line under test， as an example， when the residual stress grows from 0 to 300 MPa， the critical crack size grows by about 2.5% and the remaining life decreases by about 6%; and when the residual stress is 200 MPa， with the temperature stress from 0 to 200 MPa， the critical crack size does not change much and is within 1%. 【Conclusion】The research results of the article can provide reference for the research and maintenance of rail bottom crack propagation.

Key words： rail; rail bottom cracks; crack growth; residual stress; temperature stress

Citation format： ZHOU Y， WANG M Y， LIANG X， et al. Analysis of factors affecting the growth of rail bottom cracks[J]. Journal of East China Jiaotong University， 2024， 41（2）： 95-101.

【研究意义】钢轨伤损是影响铁路安全运行及维护的重大问题之一，特别是在轨底有初始伤损，车轮荷载通过时，轨底进一步受拉，给行车安全和钢轨使用状态带来严重威胁[1]。轨底伤损一般源于制造和铺设时的碰撞与运营中的腐蚀。其中，钢轨制造时产生的轨底伤损在出厂时能够被检验发现，风险可控。而在钢轨服役时由其所处环境引起的轨底锈蚀、轨底划痕等伤损，若探伤不及时，钢轨状态会因此迅速恶化，有断轨风险。

【研究进展】现有的无损检测技术[2-3]为钢轨轨底伤损及其次生裂纹的研究提供了基础，轨底锈蚀和划痕最初在钢轨横断面上呈半圆形。……