Model tests on dynamic response of XCC pile-raft composite foundation under different embankment heights

In order to investigate the influences of embankment height on the dynamic response of pile-raft composite foundation, a large-scale model test on the cast-in-situ X-shaped concrete (referred to as XCC) pile-raft composite foundation is carried out in a model box of 5 m× 4 m×7 m. Four different embankment heights are modeled as the dead loads, and the cyclic wheel axle load is applied to the raft so as to obtain the dynamic response with the dead loads (i.e., embankment height). The results show that the velocity response decreases by 34% ~ 40% from the top of the raft to 0.36 m depth of foundation due to the existence of a gravel cushion. The vibration of the raft caused by the axle load decreases gradually with the increasing dead loads. The relationship between the velocity response of the raft v' and the dead load x is defined by the equation, v' = 12.648-0.519x+0.007x². Both the dynamic soil stress on the surface of the foundation σ_sd and the dynamic stress at the top of the pile σ_pd decrease linearly with the increasing dead loads x. The former is defined by the equation σ_sd= 7.629-0.085x, whereas the latter is defined by σ_pd= 284.978-3.660x.