ALE FE analysis of a laboratory test for the simulation of mechanised tunnelling in soft soil

Numerical analyses of mechanised tunnel excavation are normally performed through an extremely simplified simulation of the physical processes occurring during Tunnel Boring Machine operation. Furthermore, the volume loss and the width of the settlement trough in greenfield conditions are assumed a priori and serve as a reference for the calibration of the fictitious boundary conditions prescribed to simulate the tunnel excavation. In this paper the Arbitrary Lagrangian Eulerian (ALE) method is applied in finite element analyses of mechanised tunnelling in order to predict the soil response in steady-state conditions, including the volume loss, using only the geotechnical model and the operational parameters of the TBM as an input. The proposed method is validated through the simulation of laboratory scale tests of tunnel excavation with a model Earth Pressure Balance shield. Parametric analyses are performed in plane strain on a longitudinal section of the excavation.