列车荷载下简支梁桥上CRTSⅡ型板式无砟轨道经时力学性能研究

Time-dependent Mechanical Properties of CRTSⅡ Slab Track on Simply Supported Beam Bridge under Train Load

基于混凝土和CA砂浆材料的静力与疲劳损伤本构模型及界面内聚力模型,建立简支梁桥上CRTSⅡ型板式无砟轨道精细化空间有限元模型。采用等效静力法,通过对双线列车荷载作用下结构体系各层材料单独和共同疲劳损伤劣化的分析,揭示简支梁桥上CRTSⅡ型板式无砟轨道结构体系经时力学性能演化规律。研究结果表明:双线列车疲劳荷载作用下,梁体疲劳损伤会使结构整体刚度明显下降,而轨道结构疲劳损伤对整体刚度影响较小;各层材料的疲劳损伤引起应力重分布,且随着疲劳次数的增加纵向应力呈疲劳三阶段变化趋势;轨道结构各层单独退化对梁体应力影响较小;CA砂浆纵向应力变化对各层材料的疲劳损伤都较为敏感;各层材料共同损伤对轨道板及CA砂浆应力水平影响较大且对结构整体刚度的下降产生“1+1>2”的效果。实际工程中应偏于安全,考虑CA砂浆在内的各层材料共同疲劳损伤劣化。

Based on the static and fatigue damage constitutive model of concrete and CA mortar materials and interface cohesive zone model,a refined spatial finite element model of CRTSⅡslab track on simply supported beam bridge was established.Based on the equivalent static method,an analysis was performed on the individual and joint fatigue damage and deterioration of each layer of the structural system under train load to reveal the dynamic evolution of the mechanical properties of the structural system of the CRTSⅡ slab ballastless track on the simply supported beam bridge.The results show that under double-track fatigue load,the fatigue damage of the beam will lead to a serious stiffness degradation of the structure,while the fatigue damage of each layer of the track structure has little effect on the overall stiffness of the structure.The fatigue damage of the materials of each layer causes the stress redistribution and the longitudinal stress shows a three-stage fatigue trend as the number of fatigue times increases.The independent degradation of each layer of the track system has little effect on the stress of the beam.The change in the longitudinal stress of CA mortar is sensitive to fatigue damage of each layer of materials.The joint damage of each layer of the materials has a greater impact on the stress in the CA mortar and the track slab and results in a“1+1>2”effect on the stiffness degradation of the structure.In actual projects,safety should be emphasized and it is necessary to consider the joint fatigue damage and deterioration of all layers of the materials including CA mortar.