Limerick Tunnel

t122-limerick-tunnel
Limerick, Ireland
HEIGHT: 8.5m
WIDTH: 22.75m 25.25m including toes
TOTAL IMMERSED LENGTH: 500m
DEPTH AT BOTTOM OF STRUCTURE: Water depth approx 6m below MWL Bottom of structure at approx. -16m
ENVIRONMENTAL CONDITIONS:
Ground water aquifer had to be protected from saline intrusion. Continuity between river and
ground water had to be prevented.
FABRICATION METHOD:
Reinforced concrete segmental tunnel.
Single cycle of construction of tunnel elements in approach
ramp on north side.
t122
NRA (National Road Authority)
Direct Route Concession (Sisk, Lagan, Roadbridge, Strabag)
Capita Symonds (United Kingdom)
100m
500m
16m
2010-05-01
5
7.5m wide dual 2 lane carriageway (2x3.75m lanes) with 0.15m near and offside edge strips, and 0.975m near and offside footways.
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