Effect of the constitutive material model employed on predictions of the behaviour of earth pressure balance (EPB) shield-driven tunnels

Abstract

Abstract Earth pressure balance (EPB) shield-driven tunnelling involves a complex soil-structure interaction problem, where performance is heavily influenced by stress history and its development during construction. Numerical modelling must therefore focus on selecting appropriate constitutive models for soils and structures, simulating construction procedures and sequences, and modelling the soil/structure interface. Reliable numerical models to predict expected settlements, lining pressures and other design parameters are essential for safe tunnel design. This paper discusses these factors in detail by utilizing a well-documented case study of twin tunnels in Shanghai. A 3D finite element model of the behaviour of reinforced concrete tunnel linings is developed using the new PLAXIS concrete model. Predictions of four different advanced soil constitutive models are compared with measured field results to assess the model effectiveness and suitability. The undrained behaviour of the saturated soft silty clay soil at the tunnelling site is studied during and after advancement of the shield tunnelling machine. The comparison matrix includes surface settlement troughs along transverse sections, and changes developing in earth and pore water pressures around the tunnel. The HSSmall soil model, which accounts for increased soil stiffness at small strains, was found to be the most suitable for addressing these problems.