接缝弱化后纵连板式无砟轨道温度效应研究

Study on Temperature Effect of Longitudinally Connected Slab Ballastless Track After Joints Weakening

目前,纵连板式无砟轨道夏季高温胀板问题严重。高温产生的巨大温度应力导致轨道结构发生众多病害,其中,轨道板上拱尤为严重,已威胁高速列车的运营安全。为有效释放结构内部的温度应力,减少病害发生,通过建立设有弹性填充层的纵连板式无砟轨道计算模型,引入内聚力单元和混凝土损伤塑性本构,探讨两种节段长度及不同弹性模量下,整体温升作用时,宽窄接缝弱化对轨道结构应力、变形及损伤的影响。研究表明:(1)设置弹性填充层后,轨道板和接缝的纵向应力均得到一定程度释放,但会伴随着发生局部偏心和应力增加;(2)弹性填充层的设置会使接缝、轨道板和层间界面损伤产生的临界温升降低,结构损伤较大时,轨道板和接缝的应力释放会受到限制,并且弹性填充层附近也会产生一定上拱增量;(3)两种节段长度下,损伤和应力释放量均会随着弹性模量降低逐渐增大,因此,节段长度为4块板时,弹性填充层弹性模量选取建议高于1775 MPa并低于3550 MPa,节段长度为3块板时,弹性填充层弹性模量选取建议高于355 MPa并低于1775 MPa;(4)两种节段长度下,随着弹性模量降低,轨道板和钢轨最大上拱增量逐渐增大,对于钢轨,两种节段长度下的竖向位移均在规范允许范围内。

At present,expansion plate problem of longitudinally connected slab ballastless track in summer is serious.The huge temperature stress caused by high temperature leads to many damages to track structure,especially the arch on track plate,which threatens the operation safety of high-speed train.In order to effectively release the huge stress produced by the high temperature and reduce the occurrence of damages,a calculation model of the longitudinally connected slab ballastless track considering elastic filling layers is established,which introduces cohesive element and concrete plastic damage.The influence of elastic filling layer on the stress,deformation and damage of track structure is analyzed when the overall temperature rises under two segment lengths and different modulus of elasticity.Results show that:(1)After setting the elastic filling layer,the longitudinal stress of track plate and joint is released to a certain extent,but accompanied by local eccentricity and stress increase;(2)The setting of elastic filling layer will reduce the critical temperature rise of damage of joint,track plate and interlayer interface.When the structural damage is large,the stress release of track plate and joint will be limited and the arch increment will also occur near the elastic filling layer;(3)Under both segments lengths,the damage and stress release gradually increase with the decrease of the elastic modulus.Therefore,when the segment length covers four plates,the elastic modulus of the elastic filling layer is recommended to be higher than 1775 MPa and lower than 3550 MPa.When the segment length extends to three plates,the elastic modulus of the elastic filling layer is recommended to be higher than 355 MPa and lower than 1775 MPa;(4)With the decrease of elastic modulus,the maximum arch increment of track plate and rail increases gradually.For rail,the vertical displacements of both segments are within the allowable scope of code.