Tunnel modelling: Stress release and constitutive aspects

摘要

Tunnel construction in soft ground has evolved significantly over the last 20 years, especially onrnthe matter of settlement control. This was achieved by guiding theTBM operation to control the main factors thatrninduced soil displacements, like the face pressure and the soil-lining void closure. However, the design methodsrnand numerical modeling procedures where not adapted to these new conditions, sometimes applying boundaryrnconditions, constitutive parameters or state variables with no physical meaning to match field measurements.rnThis paper presents an analysis of the basic principles of plane strain numerical modeling of tunnel construction.rnThe literature review is followed by an analysis of the stress release factor and the effects of different constitutivernmodels to represent the soil. The tunneling convergence and settlement trough as well as the stress paths on soilrnelements at the crown and at springline will be presented.