Monitoring and analysing pressures around a TBM

The excess pore pressure in front of a TBM is described for a slurry shield as well as an earth pressure balance (EPB) shield when drilling in saturated sand. Excess pore water pressures are described by using Darcy’s law and theory to describe slurry behaviour. Measured pore pressures close to the TBM are explained for various phases of the tunnelling process. Grout pressures were measured and the possibility how these can cause deformation of the tail shield is discussed. The results of this research has led to a better understanding of the mechanisms and were also used in practice in the design and execution of tunnel projects