预制板式无砟轨道界面脱层失效的数值模拟

Numerical Stimulation of Interface Delamination Failure for Prefabricated Slab Ballastless Track

将温度荷载简化为轨道板内的剪切荷载,分析了无砟轨道结构的层间界面破坏形式与粘结机理;基于黏聚力本构模型与水泥乳化沥青砂浆界面粘结力实验结果,建立预制板式无砟轨道结构界面有限元模型,研究剪切荷载作用下无砟轨道界面应力、界面粘结承载力、界面相对位移以及界面裂缝的演化规律.结果表明:界面剪应力与正应力纵向分布不均匀,在轨道板端部最大,且界面正应力使轨道板在端部竖向受拉;剪切荷载作用下,界面剪应力超过最大粘结强度,造成界面逐段破坏,界面最大粘结承载力为264.8 k N;轨道板相对于砂浆充填层的纵向位移随剪切荷载的增大而持续增大,最终界面出现纵向裂缝,而其竖向张开位移在界面纵向裂缝出现后反而逐渐闭合,界面发生剪切破坏导致无砟轨道结构脱层失效.

Firstly, the failure mode and adhesive mechanism of interface between different layers of ballastless trackwere analyzed by simplifying temperature load into the shear load of track slab. Then, on the basis of constructivecohesive force model and experimental bond strength parameters of cement asphalt mortar, an interface finite elementmodel of ballastless track structure was established. Finally, the evolution rules of interfacial stress, interfacialbond bearing capacity, interfacial relative displacement and interfacial cracks under the action of shear loadwere investigated. The results show that （1） both interfacial shear stress and normal stress distribute unevenly andachieve their maximums at the ends of track slab, and interfacial normal stress may result in a tension of track slabat two ends of the slab; （ 2 ） under the action of shear load, the interface fails gradually as a result of the interfacialshear stress exceeding the maximum bond strength, and the maximum interfacial bond bearing capacity is 264. 8kN;（3 ） the longitudinal displacement of track slab relatively to mortar-filling layer increases continuously with the shearload and then longitudinal cracks appear; and （4） the relative vertical opening displacement decreases after the interfacehas been cracked, followed with an interfacial shear fracture which may result in the delamination of ballastlesstracks.