ABSTRACT
ABSTRACT: Micro-tunnelling often encounters restrictions expanding into new areas. In the Netherlands, and more general in soft soils, one of the problems is the controlled boring of curves. To better understand the behaviour of the tunnel boring machine in such conditions, an analytical model has been developed, that takes translation and rotation of the TBM into account. The model takes the subgrade reaction and the stiffness of the soil into account as major parameters describing the soil behaviour. It is shown that the subgrade reaction in the inner and outer curve of the TBM differs substantially and a subgrade reduction factor is introduced in the model to deal with this effect. A first derivation of the subgrade reduction factor was made comparing field measurements with model parameter variations. In this paper a full three-dimensional finite element simulation is presented, using large deformation analysis to model the movement of the TBM through the soil, which has been used to study the behaviour of the micro-tunnel machine in more detail and derive the subgrade reduction factor.
