高速铁路黄土路堤结构动力响应数值分析

运用FLAC3D内置FISH语言编程实现列车荷载的施加，分析了两种黄土路堤结构在动荷载下的响应特征，并探讨桩板结构桩间距对路堤动力响应的影响。结果表明:桩板结构路堤各层的竖向位移均比无桩板结构的大；两种模型的动应力均沿线路横向呈马鞍型不均匀分布，轨下位置处动应力最大，桩板结构路堤峰值动应力比无桩板结构的大；桩间距为4 m时，基床表层表面位移最大，桩间距为3，2 m时，基床表层位移基本一致，并且比4 m时小，桩间距在2~3 m时基床表层表面位移较小。通过模拟结果发现，无桩板结构路堤动力响应比桩板结构路堤的小，在不考虑别的因素条件下，采用无桩板填土路堤结构较为合理。

Numerical Analysis of Dynamic Response of Loess Embankment Structure along High-speed Railway

In virtue of programming in FLAC3D built in FISH language to apply train load, the response characteristics of two loess embankment structures under dynamic load were analyzed, and the effect of pile spacing in pile-slab structure on the dynamic response of embankment was discussed. The result shows that, the vertical displacement of each layer of the embankment in pile-slab structure is greater than that free of pile-slab structure; the dynamic stress of the both models present saddle-shaped uneven distribution laterally along the line, and the dynamic stress beneath the rail is maximum, the peak dynamic stress of the embankment in pile-slab structure is greater than that free of pile-slab structure; where the pile spacing is 4 m, the surface displacement of the surface layer of subgrade bed is maximum, where the pile spacing is 3 m or 2 m, the displacement thereof is substantially the same and less than that in the case of 4 m and, where the pile spacing is 2~3 m, the displacement thereof is minor. Depending on the simulation result, it is found out that the embankment free of pile-slab structure has smaller dynamic response than that of the embankment in pile-slab structure, therefore, it is reasonable to adopt the embankment structure filled without pile-slab, providing no other factors are considered.