Abstract: The dynamic characteristics of X-section cast-in-situ concrete (XCC) pile-geogrid composite foundation under half sine wave loading simulating different static and dynamic loads from a moving vehicle axle are investigated in large-scale model tests. The dynamic stress of an XCC pile, soil arching, dynamic soil pressure, the stress transfer coefficient of the cushion, dynamic strain of the geogrid are analyzed. The mechanism of XCC pile-geogrid composite foundation influenced by the static and dynamic loads of vehicles is preliminarily revealed. The test results show that the influence depth of dynamic loads on stress of an XCC pile is 2 meters. More dynamic stresses are supported by the soil between piles and the effect of a geogrid on the road shoulder is weakened with the increasing of the static and dynamic loads. The stress transfer coefficient of the cushion located in the center of subgrade is constant with the increasing of the static and dynamic loads. The cumulative deformation of a geogrid increases rapidly with the increasing of the static and dynamic loads as the value of the ratio of dynamic strain is over 0.048.

Key words: pile-geogrid composite foundation, XCC pile, static load of vehicles, vibration load, model test