Soil arching effect in geogrid reinforced pile supported embankment under train dynamic load is studied by 3D model tests. Based on the test results

it is found that the soil arching effect remains valid under dynamic loading and the soil arching effect will be enhanced when the fill height increases and the existing geogrid will also enhance the soil arching effect. However

the dynamic stress distribution in geogrid reinforced pile supported embankment under dynamic loading is entirely different from the stress distribution under dead weight. The soil arching will degenerate under dynamic loading

which manifests that a part of dynamic stress previously carried by piles will transfer to soil between piles during dynamic loading applied and the dead load initially carried by piles will also transfer to soil between piles after finishing dynamic load application. The fill height and geogrid have large influences on soil arching under dynamic load; but when the fill height reaches a certain height

the influence of fill height on soil arching will be negligible; the influence of dynamic load on soil arching is weakened by half by geogrid.