Investigation of ground behaviour under pile-raft foundation applied vertical load due to tunnel excavation

Tunnel is a very useful technique to meet demands of infrastructure by population growth in the urban area. In addition, it is more important to develop underground space by environmental issue. In urban area, there are so many buildings that are constructed by pile foundation. Pile raft system is one of the pile foundations and it is foundation system rigidly connecting a raft with piles, the raft is able to deconcentrate overburden load and piles perform to keep settlement. In this paper, numerical analysis is carried out to investigate ground behaviour due to tunnelling under applied a vertical load on the pile raft system. It is assumed that tunnel diameter is D and offsets between pile toe and tunnel crown are 0.5D, 1.0D, 1.5D, 2.0D and 2.5D. Ground condition is assumed as dry medium sand. Finite element method was used for numerical analysis and conducted as plane strain condition for laboratory model test which will be simultaneously carried out close range photogrammetric technique to estimate deformation of underground induced by tunnelling.