Research on the Damage Characteristics of Double-Block Ballastless Track Bed Slab under Temperature and Vehicle Dynamic Loads
Research on the Damage Characteristics of Double-Block Ballastless Track Bed Slab under Temperature and Vehicle Dynamic Loads
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发表时间：
2012
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通讯作者：
Cai Chengbiao
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作者：
Cai Chengbiao
采用混凝土损伤塑性模型来描述双块式无碴轨道道床的力学特性。以变温条件下道床的最大损伤状态为初始条件，以车辆-无碴轨道耦合动力学模拟得到的轨支承力作为轨道-路基结构的外激励，分析了在变温和车辆动载共同作用下，道床的损伤演化规律以及道床对结构力学行为的影响。结果表明，在降温过程中，道床会发生横向弯曲变形，产生损伤，削弱其抗拉能力。由于降温产生的拉伸损伤无法恢复，轨道板的损伤值不变，保持在0.23左右，但轨道板的弹性刚度出现恢复现象。车辆通过损伤轨道板时，轨道板内部裂纹交替呈现张开或闭合的状态，弹性刚度在短时间内部分恢复，刚度退化因子最大幅度为0.057，而轨道板的损伤值保持不变。轨道板的位移和加速度、支撑层和基床表面的动应力均增加，拉应力减小，与未损伤情况下的结果相比，损伤塑性模型能较好地反映道床面板混凝土的软化和刚度退化行为。
The concrete damaged plasticity model was adopted to describe the mechanical characteristics of double-block ballastless track bed slab.Setting the maximum damaged state of track bed slab under changing temperature as the initial condition and taking the rail supporting force obtained by vehicle-double-block ballastless track coupled dynamic simulation as an external excitation of track-subgrade structures,the damage evolution law of track bed slab and the influence of track bed slab on the mechanical behavior of structure were analyzed under the joint action of changing temperature and vehicle dynamic load.Results show that the track bed slab presents lateral bending deformation and produces damage which weakens the tensile capacity in temperature dropping process.While in the temperature rising process,the damage value of track bed slab remains unchanged and keeps around 0.23 due to the tension damage produced by temperature dropping is unrecoverable,but the elastic stiffness of track bed slab appears recovery phenomenon.As vehicle passes through the damaged track bed slab,the internal cracks of track bed slab take on open or closed alternatively.The elastic stiffness is partly recovered for a short time and the maximum amplitude of stiffness degradation factor is 0.057,while the damage value of track bed slab remains unchanged.The dynamic amplitude including displacement and acceleration of track bed slab,the dynamic stress of supporting layer and the surface of foundation bed are all increased,but the tensile stress is decreased,compared with the results of undamaged condition.The damaged plasticity model can well represent the softening and stiffness degradation behavior of concrete of track bed slab.