Three-dimensional centrifuge modelling of the effects of tunnelling on vertical behaviour of pile group

Abstract

In densely built urban cities, tunnels are likely to be constructed adjacent to existing deep foundations. Tunnelling activity inevitably induces soil stress changes and soil movements in the ground, which may affect nearby existing pile foundation. Although a number of studies have been carried out by various researchers to investigate tunnelling effects on piles, the three-dimensional effects of tunnelling on pile group have not been well-investigated and understood. In this paper, a three-dimensional centrifuge test was carried out to investigate the effects of tunnel construction on a pile group in dry sand. The diameter of each pile was designed as 0.8m (in prototype) and the diameter (D) of the simulated tunnel is 6.08m. Tunnel advancement was modelled in-flight by controlling a volume loss of 1.3%. The tunnelling process was divided into four stages to model the three-dimensional tunnelling effects. The closest distance between the tunnel and the pile group was 1.5m at the pile toe. Measured settlement of pile group, as well as axial force distribution of piles in the pile group are reported and discussed.