Subproject B1 "Multimaterial modular segmental lining systems for adaptive, robust tunnel lining"

1st project phase (July 2010 until June 2014):
Segments are individual reinforced concrete elements prefabricated in the precast plant, which are assembled into a ring by the erector of the tunnel boring machine. In single-shell construction, they form the final lining. In their construction and final state, segments are subjected to a large number of stresses. At least locally, they are frequently stressed to or even beyond their performance limits. Partial surface loads and constraint effects, e.g. from jacking presses and local pressures at edge contacts, as well as later from punctual transverse force transmission in the cup-nock area, offsets or rotations, play a major role. Cracking and spalling resulting from this usually lead to a considerable impairment of the durability and thus the long-term use of the tunnel construction.

The aim of subproject B1 is to sustainably improve the quality standard of the segments in terms of safety, robustness and durability, initially by using steel fiber concrete and, in a next step, by developing a new type of segment in terms of durability. Interacting numerical and experimental methods will be used and the segmental system will be considered holistically at the material, component and process levels and optimized topologically.

2nd project phase (July 2014 to June 2018):
The aim of the subproject in the 2nd phase is to holistically optimize hybrid tubbings in terms of materials, manufacturing, robustness and permanent load-bearing capacity. This will build on the fundamental investigations into the use of fibers in tubbings and essential process developments for design optimization from the 1st funding period. The optimization not only refers to stresses from the final state of the tunnel, but also includes the deformation and load constellations of the construction stages in order to reduce susceptibility to damage in the construction and at the same time keep design-relevant allowances of the construction stages to a minimum. The investigations in SP B1, which focus on optimization-based design, robustness testing and experiments, are closely coordinated with SP B2, which carries out detailed numerical simulation calculations for the individual sub-steps.

3rd project phase (July 2018 to December 2022):
The aim of the 3rd funding phase is to further develop the methods and elements of hybrid lining systems developed so far, including their specific manufacturing processes, into modularized lining systems on a real scale, to further develop them consecutively into multimaterial, adaptive multilayer systems for use in fault zones with increased rock deformations, and to experimentally demonstrate the improvements achieved compared to classical concepts at the material level and on prototype overall components.

Research line 2 (Bausofftechnik) focuses on the development and characterization of suitable materials for the compressible additional layer. It is essential that these materials remain almost elastic under the initial effects (e.g. the annular gap compression pressure), i.e. that they have sufficient stiffness. In the face of later rock pressure under the then triaxial boundary conditions, they behave plastically after exceeding a defined stress level. Primarily, cementitious materials with different porosities (e.g. by light aggregate, foam additives, etc.) are intended, which can be adapted to the respective compression requirements by appropriate combinations. In addition to the material engineering investigations, approaches for the production of segments with these multimaterial, adaptive multilayer systems are also included.

Key publications