Special segments at the cross passages in the Filder Tunnel – Interpretation of the data from monitoring segments

Abstract

AbstractThe 9,468 m long twin‐bored Fildertunnel is the longest railway tunnel of the Stuttgart 21 project. The maximum overburden is approximately 220 m, the tunnel tubes lie up to 60 m below the water table and the distance between the cross‐passages is approximately 500 m. The precast concrete segments for the mechanised excavation of the Fildertunnel are equipped with measuring devices in proximity of the cross‐passages to assess the lining strains prior to the construction of the cross‐passages and to serve as a basis for the further design. The lining stresses are derived by applying an appropriate calculation method, which transforms the measured strains into material stresses, hence achieving the active load configuration. The strains measured on the outside and inside of the lining with embedded vibrating wire strain gauges are converted into stresses and internal forces, enabling a direct assessment of the internal forces along the entire circumference of the segmental lining. In this article the measurement results in the area of the cross passages 6a and 7a of the Fildertunnel are described and interpreted. The significant internal forces in the segments after their installation and their time development are described, their dependence on influence factors such as self‐weight, thrust forces, grout pressure, rock mass and water pressure is discussed and the results are compared to the design calculation.