板式无砟轨道锚穴部位损伤分布研究

Damage Distribution at Anchor Pockets in Slab Track

在列车荷载及环境因素的长期作用下,轨道板锚穴部位易产生裂纹,对轨道结构服役性能可能产生不利影响。本文介绍了轨道板预应力的张拉施工过程,并基于损伤力学与混凝土塑性损伤模型,建立了纵、横向预应力作用下的轨道板锚穴部位损伤分布模型,以最大主拉应力、压缩损伤因子及拉伸损伤因子为评价指标,分析了轨道板在预应力施加过程中锚穴部位裂纹损伤的分布状况。结果表明:预应力作用下,纵向锚穴部位最大主拉应力为2.47 MPa,相较于横向锚穴更容易产生初始裂纹损伤;预应力作用下,锚穴部位压缩损伤因子均不超过0.5,压缩损伤范围较拉伸损伤范围小;相较于横向锚穴,纵向锚穴部位拉伸损伤范围已基本扩散至轨道板上下表面,最大拉伸损伤因子可达0.9,应重点关注。

As a result of long-term exposure to train loads and environmental factors,the crack damage around anchor pockets in slab track will occur,which can adversely affect the mechanical performance of track structure.In this paper,the post-tensioning process of prefabricated track slab was introduced.Moreover,based on damage mechanics and the Concrete Damage Plasticity(CDP)model,the damage distribution model of anchor pockets under longitudinal and transverse pre-stress was established.In an attempt to study the crack damage distribution around anchor pockets during prestressing process,the maximum principal tensile stress,compression damage factors and tensile damage factors were selected as evaluation indexes.The results indicate that:the maximum principal tensile stress around longitudinal anchor pockets under the action of pre-stress is 2.47 MPa,which is more likely to cause initial crack damage than that of transverse anchor pockets.The compressive damage factors of anchor pockets under pre-stress are all less than 0.5,with the compressive damage area smaller than the tensile damage area.Compared with transverse anchor pockets,the tensile damage of longitudinal anchor pockets spread to the upper and lower surfaces of the track slab with the maximum tensile damage factor reaching 0.9,which should be highly focused on.