基于混凝土塑性损伤模型的轨道板损伤规律

Damage law of track slab based on concrete damaged plasticity model

基于混凝土塑性损伤模型,建立CRTSⅠ型轨道板损伤分布计算模型,将Tekscan传感器测得的钢轨支点压力作为荷载输入,以轨道板竖向位移及拉伸损伤因子作为评价指标,分析客货共线条件下水泥乳化沥青(CA)砂浆离缝状态时锚穴周边轨道板上表面混凝土的内部损伤规律.结果表明:随着离缝长度的不断扩展,损伤产生及完全损伤的临界离缝高度均逐渐变小;当离缝长度扩展至第2、3锚穴时,客车荷载下损伤产生的临界离缝高度分别约为0.8、1.0mm,货车荷载下约为0.5、0.8mm;一旦超出损伤产生的临界离缝高度,由于轨道板损伤的发展,轨道结构整体抗弯刚度迅速降低导致板端竖向位移迅速增大;对于客车荷载,当离缝扩展至第3锚穴且高度大于1.0mm后,CA砂浆形成脱空,板端位移不再增长,对于货车荷载,当离缝扩展至第3锚穴且高度大于1.3mm后,由于二次损伤带的产生,板端竖向位移随离缝高度的增大迅速增大.

Based on the concrete damaged plasticity model,a CRTSⅠtrack slab’s damage distribution model was established.The rail supporting force measured by Tekscan sensor was taken as load data,and the vertical displacement of track slab and the tensile damage factors were taken as calculating indicators.The inner damage law of the upper surface of track slabs near anchor pockets was analyzed when the debonding was between cement and emulsified asphalt(CA)mortar and track slabs existed in the passenger-freight line.Results showed that the critical heights of debonding for both initial damage and complete damage gradually decreased with the extension of the debonding length.When the debonding reached to the second and third anchor pockets,the critical heights of initial damage generated by the load under passenger car were about 0.8 mm and 1.0 mm,respectively;meanwhile,the critical heights under freight car were about 0.5 mm and 0.8 mm,respectively.Once the height of the debonding was greater than the critical height of initial damage,due to the development of the damage of track slab,the overall bending stiffness of the track structure decreased rapidly,resulting in a rapid increase of the vertical displacement of the slab end.Under the load of passenger car,after the debonding reached to the third anchor pocket and the height of the debondong was more than 1.0 mm,the CA mortar was formed into a void,and the displacement of the slab end did not increase any more.Under the load of freight car,when the debonding reached to the third anchor pocket and the height of the debonding was more than 1.3 mm,the vertical displacement of the slab end increased rapidly with the increase of the height of the debonding,due to the generation of the secondary damage zone.