Long-term settlement induced by EPB tunnelling studied with numerical simulations

Abstract Long-term settlement induced by tunnelling in soft cohesive subsoil is rarely considered as a subject for research despite substantial evidence that it increases considerably after construction. The paper aims to investigate the time effects of tunnelling with an earth pressure balance (EPB) shield by means of analysing subsoil deformation with the most up-to-date numerical tool. A three-dimensional numerical model with a detailed description of the geometrical and mechanical characteristics of the tunnelling process and the various materials involved was built. The computational model validated on a real-case was then used to simulate tunnelling in different groundwater conditions prior to construction. That was followed by a simulation of groundwater drawdown conditions after tunnelling with impermeable and permeable tunnel linings. The calculations show the development of the settlement over time in different groundwater conditions together with the significant influence of the permeability of the tunnel.