A holistic approach for the investigation of lining response to mechanized tunneling induced construction loadings

Abstract Design methods for segmental tunnel linings used in mechanized tunnel constructions typically employ numerical bedded beam models and/or classical analytical solutions for the determination of structural forces (i.e. moments and shear and axial forces) and simple load spreading assumptions for the design of the reinforcement in joint areas. However efficient such methods may be, many physical details are often overlooked and/or oversimplified in the process of reducing the actual structure to a structural beam model, e.g. analytically derived loadings are employed, the grouting and ground reactions are reduced to a spring bedding, and the confinement due to grouting at the longitudinal joint is largely not considered in reinforcement design. Such a design process is not able to account for, or predict, the susceptibility of tunnel linings to often observed damages that, although they may not be structurally relevant, lead to serviceability or durability issues, such as crack development or chipping at the segment corners. Numerical methods, such as the Finite Element Method, provide an opportunity to model the segmental tunnel lining and its response to the entire TBM construction process and to explicitly model the crack development within individual segments using modern methods to model the discontinuities in structures. In this contribution, a holistic modeling procedure for the representation of the tunnel lining within the tunneling process is proposed and compared to traditional lining models. A 3D process oriented Finite Element model is used to calculate the predicted forces on the tunnel lining and the obtained results are compared with those generated by traditional methods. Subsequently, the predicted deformations are then transferred to a detailed segment model in which the nonlinear response of the segment at the longitudinal joint is modeled using an interface element based approach to simulate concrete cracking.