Dynamic response of XCC pile-geogrid composite foundation of expressways influenced by vehicles with different speeds

Based on the large-scale model test system, dynamic model tests on geogrid-reinforced XCC piles-supported embankment of expressways under traffic loads are carried out. The dynamic parameters under the vehicles different speeds are monitored. The variations of dynamic stress distribution, dynamic stress diffusion, geogrid dynamic strain, geogrid cumulative strain and differential settlement are studied. The results show that the amplitude of dynamic stress above soils fluctuates near the geogrid in the case of high and low speeds. There is a little difference in the additional load of the vehicle with high speed. The dynamic strain of geogrid remains stable in the case of high speed. The stress transfer coefficient of the cushion located in the center of subgrade is larger than that near the shoulder. The relationship between the dynamic strain and the cumulative strain of geogrid can be described by the linear function, and the cumulative deformation of geogrid is mainly produced under low speed. The amplitude of dynamic stress of a XCC pile increases with the increasing speed, and its axial force is smaller than that of the circular pile.