Numerical Analysis of Ground Movement due to shield tunneling at Nape, Macau

Abstract

With the rapid development and urbanisation worldwide, intensive underground infrastructures are built through dense urban areas due to risk control and environmental protection. The shield tunnelling method has been widely adopted for fast and safe construction where traditional methods cannot be implemented. However, the occurrence of ground movements during tunnel construction is inevitable. Serious ground movement leads to the tunnel collapsing and deaths. Hence, ground movement is a vital controlling parameter for tunnel construction analysis. In this study, a finite element model simulating the first shield tunnel in Macau – the NAPE sewage tunnel pipe is established by the software PLAXIS 2D to investigate the ground settlement. Both linear elastic and Mohr-Coulomb material models are adopted in the simulation. It is found that the result obtained from PLAXIS 2D matches with the surface settlement estimated by the empirical and analytical solutions, verifying the reliability of the numerical solution. The result is then compared with the field measurement data. Though a slight difference exists between the results due to the limitations of simulating the real site condition, the numerical data is believed to be acceptable. Besides, the outcomes of the two material models are contrasted. The Mohr-Coulomb model is more suggested as it considers further on the plastic behaviour of the soil, which is necessary for tunnel analysis.