Deformation measurements of tunnel segments at a newly developed test rig / Deformationsmessungen an Tübbingen mit einem neu entwickelten Prüfstand

Abstract

Deformation measurements of tunnel segments at a newly developed test rig Deformationsmessungen an Tübbingen mit einem neu entwickelten PrüfstandWith the use of tunnel boring machines under different geological and geotechnical conditions, the support with precast elements has been state of the art for decades. For the verification of the load-bearing and deformation behaviour of these high-strength reinforced concrete elements under exact known loading conditions, a test rig has been developed and implemented in a cooperation between experts of Austrian Federal Railways (ÖBB-Infrastruktur AG, SAE Fachbereich Bautechnik/Tunnelbau) and the Montanuniverität Leoben (Chair of Subsurface Engineering). The newly developed segment test rig allows biaxial tests on real segments. Due to the modular construction it is feasible to test segments with different geometries and dimensions. The obtained findings should be included in the optimization of these elements. Furthermore, the optimisation of the reinforcement design and replacement of steel bar reinforcement with fibre reinforcement is being investigated. With this test rig, an important step has been taken towards new technologies and materials in the field of segment linings. Currently, tests with distributed fibre optic sensing systems are carried out in cooperation with the Graz University of Technology (Institute of Engineering Geodesy and Measurement Systems -IGMS). A fibre optic sensing cable can be embedded in the segment during production and used for lifelong in-situ deformation measurements of the segment.

Current status of tubbing research – Insight into the research activities at the Chair of Subsurface Engineering

“…It should be stated that this stress in the post-fracture area is to be understood more for comparison between different tests and does not represent a mechanical quantity. Instrumentation of the segments with fibre optic sensor cables showed that the cracks form directly at the position of the cross reinforcement [1]. In order to check whether there is weakening of the segment due to the given crack position, a modified reinforcement cage with solely bending reinforcement without cross or splitting tension reinforcement in the central part ( Figure 5) was selected for the production of one segment (test 15).…”

“…The electro-hydraulic test rig (Figure 1) consists of a fixed (2) and a floating bearing (3), bolted to the main beams (1). This modular construction enables the testing of segments with various dimensions and geometries.…”

“…In order to obtain conclusions about the load bearing and deformation behaviour of installed segments, tests are necessary under laboratory conditions with defined support conditions and loading cases. For this purpose, a segment test rig has been developed at the Montan University Leoben -Chair of Subsurface Engineering in collaboration with the Austrian Federal Railway (ÖBB Infrastruktur AG) [1].…”

In‐situ assessment of strain behaviour inside tunnel linings using distributed fibre optic sensors

“…Dieser ermöglicht die Untersuchung von Tübbingen im Realmaßstab unter kontrollierter, biaxialer Belastung [11]. Dieser ermöglicht die Untersuchung von Tübbingen im Realmaßstab unter kontrollierter, biaxialer Belastung [11].…”

“…To verify the utilization of pre-cast tunnel segments, the Austrian Federal Railways in cooperation with MUL developed a special test rig (Figure 4a). The realized facility enables investigations of full-scale segments under controlled, bi-axial loading [11].…”