Upgrading Dock Barrow

Upgrading Dock BarrowAs a result of the increasing size of the submarines being built on the Vickers wharf at Barrow, deepening of the dock basin was required. The main consequence of this was the necessity to build a new dock entrance. This entrance consists of a lock that separates the dock basin from the extreme tidal action in the Irish Sea.
The new entrance is a U-shaped concrete box of 50 x 50 x 26 m with a steel flap gate. When the lock is open the gate rests in a recess in the floor. The lock has been equipped with culverts, that also prevent undesirable sediment build-up. To assure stability the concrete floor has a thickness of up to nine meters. Thermal stresses and possible construction methods were important considerations in the design.
The concrete structure has been built next to the old lock, and sunk to its final position as a pneumatic caisson. To prevent damage to the existing structures, which were in close proximity, the sinking process has been very carefully monitored and controlled, especially with regard to groundwater flow. Sixteen meter high steel bulkheads were used as a temporary soil and water retaining structure during the sinking of the caisson. Specific attention was given to the required freedom of movement for the different parts of the construction.

Activities:

• all design calculations and construction drawings required for building the new dock entrance and associated works
• continuous tuning and feed-back between design and construction