Theoretical Solution for Consolidation Settlement of Pile-Net Composite Foundation Under Embankment Load

With the development of the coastal cities in China, pile-net composite foundation, which contains the components of embankment fills, reinforced cushion, geogrid and piles, has been increasingly used for highways, railways, etc. because of its effectiveness in controlling the post-construction settlement with a relatively low cost. However, the pile-net composite foundation is so complicated that few studies provide the theoretical investigation on the composite foundation. In this study, a theoretical solution was developed by fully considering the soil arching effect, membrane effect and the interactions between component parts. The finite differential method was utilized to obtain the consolidated performances of pile-net composite foundation. According to the results, it is found that (a) the stress concentration ratio and axial force of the pile increases with consolidation of composite foundation; (b) the neutral point of the pile shifts down with the consolidation process; (c) membrane effect of the geogrid also has a obvious influence on the stress concentration ratio and (d) ignoring membrane effect will underestimate the pile stress ratio. Furthermore, the theoretical solution is used to compare with the finite element modeling to illustrate its feasibility.