Investigation of Tunnel-Soil-Pile Interaction in Cohesive Soils

Underground tunnels are considered to be a vital infrastructure component in most cities around the world. Careful planning is always necessary to ensure minimum impact on nearby surface and subsurface structures. This study describes the experimental investigation carried out to examine the effect of existing piles installed in cohesive soil and extended to bedrock on the circumferential stresses developing in a newly constructed tunnel supported by a flexible lining system. A small scale testing facility was designed and built to simulate the process of tunnel excavation and lining installation in the close vicinity of preinstalled model piles. Lining stresses were measured for different separation distances between the lining and the existing piles Consistent decrease in the lining load was observed when the piles are located within a distance of one tunnel diameter from the tunnel. The results presented in this study indicated that measuring the lining response near existing pile foundations may be used to evaluate the extent of the interaction between the lining and the surrounding piles.