疲劳荷载作用下无砟轨道混凝土轨道板氯离子传输与服役寿命

Chloride Transmission and Service Life of Concrete Slab for Ballastless Track Under Fatigue Load

采用表观电阻率法研究了无砟轨道混凝土的疲劳损伤过程,分析了混凝土氯离子扩散系数随服役年限的变化规律,基于Fick第二定律修正了疲劳荷载作用下混凝土氯离子扩散模型,采用Monte Carlo方法研究了疲劳荷载与氯离子侵蚀耦合作用下混凝土轨道板的服役寿命。结果表明:无砟轨道混凝土疲劳损伤呈现三阶段发展规律,列车疲劳荷载加速了轨道板内氯离子传输,且列车疲劳荷载对氯离子扩散的加速效应主要体现在疲劳损伤的第二和第三阶段;列车疲劳荷载与氯离子侵蚀耦合作用下混凝土轨道板服役寿命可满足无砟轨道设计使用年限要求;环境温度升高增大了轨道板的失效概率,增加保护层厚度和使用耐腐蚀钢筋均可延长混凝土轨道板的服役寿命。

The fatigue damage process of concrete for ballastless track was studied by using the apparent resistivity method,and the variation law of chloride diffusion coefficient of concrete with service life was analyzed.Based on Fick second law,the chloride diffusion model of concrete under fatigue load was modified,and the service life of concrete slab under the coupling action of fatigue load and chloride ion erosion was studied by using Monte Carlo method.The results show that the fatigue damage of concrete for ballastless track presents a three-stage development law,the train fatigue load accelerates the chloride ion transmission in the track slab,and the acceleration effect of train fatigue load on chloride ion diffusion is mainly reflected in the second and third stages of fatigue damage.The service life of concrete slab under the coupling action of train fatigue load and chloride ion erosion can meet the design service life requirements of ballastless track.The increase of ambient temperature increases the failure probability of the track slab,and the service life of the concrete slab can be prolonged by increasing the thickness of the protective layer and using corrosionresistant steel bars.