高速列车荷载作用下桩网复合地基土工格栅变形特性研究 English Version
Deformation characteristics of geogrid in piled embankments under high-speed train load
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摘要: 土工格栅是影响桩网复合地基桩、土荷载分配问题的主要因素之一，但目前对其研究还不够深入，尤其是动态列车荷载作用下。为此建立了相似比为1：5的桩网复合地基模型，以作动器输出的M形波模拟列车动载，开展了格栅动态变形特性研究，揭示了列车动荷载-土工格栅-碎石-桩之间的相互作用机理。结果表明：列车经过瞬时，路堤中部、路肩下方格栅动应变时程曲线呈“正M”形，边坡处格栅动应变时程曲线呈“倒M”形。振动初始阶段格栅碎石垫层类似于“半刚性平台”，一段时间后格栅碎石垫层类似于“拉膜”。列车高速运行时，路堤中部下方和路肩下方的格栅累积应变随着加载幅值的增加逐渐单调增长；边坡坡脚处格栅累积应变随着加载幅值的增大逐渐减小。Abstract: Geogrid is one of the main factors affecting the load distribution of pile and soil in piled embankments, but its research is not deep enough, especially under dynamic train load. For this reason, a piled embankment model with a similar ratio of 1:5 was established, and the dynamic deformation characteristics of the geogrids were studied by using M-shaped wave of the actuator outputting to simulate the dynamic load of the train, and the interaction mechanism between the dynamic load of the train, the geogrid-gravel-pile was revealed. The results show that the geogrid dynamic strain time history curves under the middle and the shoulder of the embankment present a "positive M" shape, and the geogrid dynamic strain time history curves at the slope show an “inverted M” shape. The geogrid-gravel cushion behaves as a “semi rigid platform” in the initial stage of vibration, and acts as a “tensioned membrane” after a period of vibration. When the train runs at high speed, the cumulative strain under the middle and the shoulder of the embankment increases monotonically with the increase of the loading amplitude. At the foot of the side slope, the cumulative strain of the geogrid gradually decreases with the increase of the loading amplitude.
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Keywords:
- piled embankment /
- high-speed train load /
- geogrid /
- dynamic strain /
- cumulative strain
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