Physical model study of pile type effect on long-term settlement of geosynthetic-reinforced pile-supported embankment under traffic loading

In coastal area, the long-term settlement of high-way embankment is seriously concerned. Geosynthetic-reinforced pile-supported (GRPS) embankments have been widely adopted for the construction over soft soils to solve the large settlement problem. However, the long-term performance of GRPS embankment under traffic loadings is not fully understood. In this study, a series of physical model tests were conducted. Different pile types (rigid pile, rigid-flexible pile, flexible pile) and geosynthetic layers (single-layer and double-layer) were comparatively investigated. Two stages of long-term cyclic loadings were applied to simulate the traffic loadings. Based on the results, it is found that the model test with rigid pile has the least settlement, whereas the model test with flexible pile experiences the largest settlement when subjected to both 1 Hz and 2 Hz cyclic loadings. In the view of long-term settlement control, the rigid pile is the best choice for the GRPS system. The applied cyclic loadings have the lowest effect for the pile strain distribution in rigid pile model but much higher effects in both flexible pile and the rigid-flexible pile models, which demonstrates that the traffic loading after the construction of GRPS embankments may leads to unneglected stress redistributions. The findings of this study would provide the reference to consider the traffic loading effects on different pile types of GRPS embankment.