Tunnelling | Performance
Precisely fitting sealing corners
The special properties of the Performance Corner are designed to ensure the tightness of the tunnel across the different geologies and to withstand the water pressure. Correct adaptation of the corner geometry, which results from the respective segment design, is decisive for this. In this way, the perfect fit of the seal on the segment can be guaranteed. The accuracy of fit results from the combination of the correct cutting angle at the end of the profile and the correct adjustments to the opening angle α and twisting angle β, which results from the ring design of the segments. The adapted torsion angle β prevents the creation of an additional offset to the opposite gasket frame.
opening angle α and twisting angle β
The Performance Corner is characterised above all by its high flexibility. Basically, the requirements for all projects are precisely checked with regard to the required tightness and spalling behaviour and the corner geometry required as a result is determined. This includes the precise evaluation of the position of the sealing groove in relation to the outer edge of the segment. This involves deciding which gate angle is to be selected at the end of the profile with the resulting injection volume and to what extent the opening angle α and twisting angle β must be adjusted. The profile can be cut at 30°, 50° or 90° to control the injection volume.
The production of the Performance Corner allows a variable corner length and degree of hardness. As the opening angle of the corner joint can be individually adjusted, the adaptation to the segment angles prevents the gasket corner from being cut open or constricted. Precisely fitting gasket frames are created for the respective segment design.
The Performance Corners have been used since the introduction of the variable profile gating and were first used by our company in 2015. The demand for sealing frames with the precisely fitting corners has more than doubled since then.
High holding strength and reliable tightness
The injection molding process is used for manufacturing the Performance Corner, which allows significantly higher retaining forces to be generated in the corner area. These retaining forces within the sealing corner are absolutely necessary so that the high compression force between the concrete segments that occurs while sliding them in does not result in tearing or moving the corner during installation.
The use of a film butt joint, already well-known on the market for its use in manufacturing O-rings for concrete pipes and soft corners, is not suitable here because the required reset force cannot be created due to the lack of volume. The risk of potential leaks cannot be ruled out. In a worst case scenario, the gasket frame can tear when installing segments with film butt joints due to the low retaining force in the vulcanized connection.
The right material
The Performance Corner consists of EPDM, which is also the basic material of the profile itself. EPDM has demonstrated excellent characteristics: it allows for a good connection to the profile, which guarantees the required tear resistance for the frame corner during the assembly of the gasket frames and the installation of the segments. With regard to the long-term relaxation, EPDM ensures a structure is leak-tight throughout its entire service life and has very good ozone, aging, and weather resistance. For special requirements, for example soil contaminated with hydrocarbons, the Performance Center can also be made of chloroprene rubber (CR). Materials with an antibacterial effect can also be used in the construction of tunnels for drinking water and waste water drainage.