Internal forces measured in segmental tunnel linings compared with numerical predictions obtained from state-of-the-art calculation methods used in engineering practice

Different calculation methods and modeling strategies are commonly used in engineering practice to predict the internal forces in segmental tunnel linings. Accordingly, the calculation results can differ. The present paper compares internal forces resulting from five state-of-the-art calculation models, of which three continuum models and two bedded beam models, to new in-situ measurements of internal forces at the recently built TBM tunnel for the U5 metro line in Frankfurt, Germany, and discusses agreements and differences. Hereby, a generally good agreement is found for the normal forces. The predictions of the bending moments are satisfying, but there are some discrepancies. It is shown that it might be necessary to consider assembly imperfections in the calculation models to improve the agreement between the calculation results and the measurements. Also, the differences between the calculation methods themselves are addressed. It is analyzed that generally continuum models give more realistic internal forces, but that also bedded beam models can have advantages, e.g. when large parametric studies are required. Finally, recommendations are given regarding the application of calculation models for structural design.