Railroad Tunnel
Project DescriptionThis project focuses on a several hundred-meter-long railway tunnel built in the year 2001. The interior shell is constructed of steel reinforced concrete. After production of the tunnel's inner shell, local stripping and hallow locations between 0.50 m to 2.50 m long were observed above the emergency footpath by tapping the concrete surface. TaskWithin a very short window of time (4 weeks), the commissioned company had to resolve the following issues:
In order to clarify these questions, the following strategy for damage assessment was developed: ProcedureAmong other things the conducted examinations included:
From the extensive investigations it could be deduced that the strippings were always located where base/arches connect. Cause:Through the vibrations of the external vibrator in particular frequency ranges on solified concrete or concrete in the hardening phase, induced normal and shear forces caused strippings parallel to the surface (cracks) in the low-lying areas. High concentrations of reinforcement (shear sections) have certainly contributed to the extent of the damage. Solution:After identification of the stripping areas with Impact Echo, the concrete in these areas was removed and replaced with shotcrete. |   Cross-section of the tunnel inner shell with the framework, carriage and potential area with hollow layers depicted |
