板边离缝对CRTS III型轨道-路基动力特性的影响

为了研究板边离缝对高速铁路基础结构动力特性的影响，利用CRTS III型板式轨道-路基全尺寸试验模型开展了落轴试验，实测了轨道板与自密实充填层一侧界面处离缝的几何分布，并利用ANSYS/LS-DYNA有限元软件建立了相应的动力有限元分析模型，分析了板边离缝对轨道和路基结构冲击动力特性的影响规律，并利用相应的试验结果对数值结果进行了对比验证. 研究结果表明:轨道板和自密实层界面处单侧离缝的平均宽度和平均高度分别为28.18 cm和2.15 mm；板边离缝宽度对基础结构动力特性的影响要大于离缝高度；在0～800 mm的范围内，随着离缝宽度的增加，轨道和路基位移以及钢轨加速度、轨道板加速度和基床底层加速度都持续增加，其中轨道板的位移和加速度的增幅均为最大，分别为56.8%和143.3%，充填层、支承层和基床表层的垂向加速度随离缝宽度的增加先增大后减小，当离缝尖端扩展至钢轨正下方附近时达到最大值；在0～3 mm的范围内，轨道和路基垂向位移与加速度均随离缝高度的增大而略微增加，最大增幅分别为8%和12%；越靠近离缝界面层面，离缝高度对其冲击动力特性的影响也越显著. 

Influence of Interface Crack on Impact Dynamic Properties of CRTS III Slab Track-Subgrade System

To investigate the influence of the interface crack on the dynamic characteristics of high-speed railway infrastructure, a wheel-drop test was performed using the full-scale experimental platform of CRTS III ballastless track-subgrade system. The distribution of the one-sided interface crack between the slab and self-compacting concrete layer was measured and summarised. The 3D dynamic finite element model of the CRTS III track-subgrade system with a one-sided interface crack was established using the ANSYS/LS-DYNA software. The influence of the interface crack subjected to the wheel-drop load was investigated on the basis of comparisons between the experimental data and numerical results. The results indicate that the average width and height of the interface are 28.18 cm and 2.15 mm, respectively. The crack width has a stronger effect than the crack height on the infrastructure dynamic reaction. When the crack width increases within a range of 0 to 800 mm, all the displacements of the infrastructure and the accelerations of the rail and slab increase proportionally with the increase of the crack width. When the crack width approaches the distance between the rail and slab edges in the lateral direction, the accelerations of the filling layer, concrete basement, and subgrade reach their respective maxima. The maximum icrements of the displacement and the acceleration for the track and the subgrade are both occurred in the slab, which are respectively 56.8% and 143.3%. All the displacements and accelerations of the track and subgrade slightly increase with the increase of the crack height from 0 to 3 mm, and the maximum increments are 8% and 12%, respectly. The influence of the crack is more remarkable on the dynamic properties with the decrease of the distance between the infrastructure level and the crack locsation.