Deformation characteristics of geogrid in piled embankments under high-speed train load

Geogrid is one of the main factors affecting the load distribution of pile and soil in piled embankments, but the related research is not in-depth enough, especially under dynamic train load. For this reason, a piled embankment model with a similar ratio of 1:5 is established, the dynamic deformation characteristics of the geogrids are studied by using M-shaped wave of the actuator outputting to simulate the dynamic load of the train, and the interaction mechanism among the dynamic load of the train, geogrids, gravel, and piles is 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.