利用CRTSⅢ型板式无砟轨道-路基系统实尺模型开展落轴冲击试验,同时运用Ansys/LS-Dyna软件进行轨道-路基落轴冲击动力有限元模拟分析,在试验结果和数值结果对比验证的基础上,系统研究落轴荷载作用下轨道和路基结构动应力分布规律,比较落轴高度和加载位置对动应力分布的影响.研究结果表明:试验结果和数值结果具有较好的一致性,两者可以相互验证,互为补充.轨道结构各层动应力均在钢轨正下方达到最大值,动应力幅值沿线路横向分布总体上呈驼峰形分布;沿线路纵向大致呈正态分布,自密实层应力幅值在板端附近有明显地回弹.路基动应力幅值底座板宽度范围内,沿横向分布比较均匀,在底座板宽度范围外快速衰减;沿线路纵向大体上呈正态分布;路基动应力幅值沿深度的衰减速度随着深度的增加而减小,在基床内衰减较快,基本呈线性或者分段线性衰减,在路基本体内衰减非常缓慢.轨道和路基动应力幅值总体上随落轴高度增加而线性增加,但沿线路纵横向分布规律不变.相对于板中加载,板端加载时轨道和路基各层面动应力幅值均有所增大,越靠近加载点增幅越明显,但是2种加载条件下轨道和路基结构应力幅值分布规律基本一致.%A full-scale model experiments of wheel-drop impact was performed on a typical CRTS Ⅲ ballastless track-subgrade system. Its three-dimensional dynamical analysis model was established based on the software ANSYS/Ls-Dyna. The dynamical stresses distributions of overall CRTS Ⅲ track-subgrade under wheel-drop impact loads were systematically analyzed on the basis of the comparison of experimental data and numerical results. The influence of wheel-drop height and the loading cross section location on the stresses distributions were investigated. The results indicated that experimental and numerical data are very close and that the two methods can be validated and be complemented each other. The peak stress distribution of track structure along lateral direction has a hump-shape in general, and the maximum stresses in different layers are all located in the sites where the loading section crosses the longitudinal section through the rail. The stress distribution along longitudinal direction submits to normal one overall. The peak stresses of the self-compacting concrete layer rebound remarkably at the region beneath slab ends. The peak stress of the subgrade between the width ranges of concrete base fluctuates slightly, while it attenuates rapidly out of the range. The distribution of subgrade stress along the longitudinal direction presents a normal curve. The attenuation gradient of subgrade along the depth direction decreases with the increment of depth. The peak stress of subgrade bed decreases linearly or piecewise linearly along depth direction, while it shrinks very slowly in embankment. The peak stresses of track and subgrade increase linearly with the increase of the height of the wheel-drop, while the height has almost no influence on the stress distribution. When the loading section is located in the end of track slab, the peak stresses of track and subgrade in different layers are all greater than those when the loading section moves to the middle of track. However, loading section position has little effect on distributions of the peak stresses.
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