Structural Forces in Segmental Linings: Process-Oriented Tunnel Advance Simulations vs. Conventional Structural Analysis

Synopsis:

Tunnel linings are designed to permanently fulfill basic structural, serviceability and durability requirements throughout the lifetime of a tunnel. In order to ensure structural stability, it is important to correctly assess the response of tunnel linings with respect to the loading from the ground and process loads to which lining structures are subjected. For the design of segmental tunnel linings, precise structural models are needed, as the segmentation imbues the lining system with non-trivial kinematics. In this contribution, a technique for modeling the segment-wise installation of tunnel linings in the context of a 3D tunnel advance simulation is proposed in order to better predict the time dependent structural forces that develop in segmental lining systems during tunnel advance. The segments of the lining ring are explicitly modeled as separate bodies, and the interactions between segments at the longitudinal and ring joints are modeled by means of a surface-to-surface frictional contact algorithm. In order to examine the 3D stress distribution in the segmental concrete lining under realistic, time-dependent process loadings, the lining model is integrated into the process oriented finite element simulation model ekate. The influence of the joint arrangement and the segmentation is investigated through comparison with simulations in which a standard, continuous lining modeling technique is employed and with standard structural beam models used in engineering practice. It is shown that the magnitude of structural forces obtained by the explicit modelling of segmental lining joints and their time-dependent installation process within a 3D structural model diverges significantly from those obtained using standard methods, i.e. bedded beam models.

Tunnelling and Underground Space Technology 2021
Volume 111
May, 2021 (Marwan, A.; Gall, V. E.; Alsahly, A.; Meschke, G.)