Positioning pins for tunnel segment spacers
A spacer needs to be placed at the bearing point defined for the storage arrangement. Two locating pins on the underside of Green Spacers engage matching sockets cast into the concrete to help operators repeat that position.
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Why positioning matters
Spacer location determines where the support contacts the segment. Consistent positioning helps operators follow the planned bearing layout when preparing successive layers for storage.
The pin-and-socket arrangement also helps restrain lateral sliding during segment movements covered by the approved handling procedure.
From casting to correct positioning
Form the sockets
Matching mould inserts create the sockets at the specified positions. Locations are coordinated with the segment design and bearing arrangement.
Align the spacer
Check spacer and socket condition and cleanliness. Align both pins with the corresponding sockets.
Engage both pins
Lower the spacer until the pins are fully engaged and the body rests correctly on the intended concrete bearing surface.
Check the bearing
Before adding another segment or carrying out an approved movement, check orientation, contact and position against the procedure.
The pins locate. The body carries the load.
Correct pin engagement must be accompanied by correct bearing contact. The concrete sockets, spacer geometry and handling conditions are assessed together for the project.
Considering an existing mould?
An existing mould arrangement can be reviewed to establish whether and how suitable sockets could be incorporated. This requires coordination with the segment designer and mould supplier, taking account of geometry, reinforcement, bearing locations and production requirements.
