Limerick
TOTAL IMMERSED LENGTH: 500m
DEPTH AT BOTTOM OF STRUCTURE: Water depth approx 6m below MWL; bottom of structure at approx. -16m
WIDTH: 22.75m; 25.25m including toes
HEIGHT: 8.5m
VOLUME: 96688m^3
FABRICATION METHOD: Reinforced concrete segmental tunnel. Single cycle of construction of tunnel elements in approach; ramp on north side.
SITE CONDITION: River
DEPTH AT BOTTOM OF STRUCTURE: Water depth approx 6m below MWL; bottom of structure at approx. -16m
WIDTH: 22.75m; 25.25m including toes
HEIGHT: 8.5m
VOLUME: 96688m^3
FABRICATION METHOD: Reinforced concrete segmental tunnel. Single cycle of construction of tunnel elements in approach; ramp on north side.
SITE CONDITION: River
Limerick,
Ireland
(Beneath River Shannon on Limerick Southern Ring Road)
NRA (National Road Authority)
Direct Route Concession (Sisk, Lagan, Roadbridge, Strabag)
Cowi A/S (Denmark)
Capita Symonds (United Kingdom)
100m
500m
-16m
Project construction
2006-07-31
2010-05-31
5
2
8.5m
22.75m (25.25m including toes)
Tunnel roof is above water level at low tide. Required temporary tie across immersion joints during construction to maintain compression in gina gasket.
Reinforced concrete segmental tunnel. Single cycle of construction of tunnel elements in approach ramp on north side.
On site
Ground water aquifer had to be protected from saline intrusion. Continuity between river and ground water had to be prevented.
Elements constructed in on-line casting dock and winched into place. Catamaran pontoons for placing.
Gina & omega seal at immersion joints. Injectable waterstop and external waterbar at segment joints
Watertight concrete achieved by cooling during curing. No membrane applied.
Crushed limestone, using sand flow technique. Ground improvement on north side under TE5 using stone columns. Piled approach tunnels and ramps.
800mm rock armour on sand
C40, to British Standards.
1.025 temporary condition, 1.06 permanent condition