It is proposed to make a new pedestrian access running directly south from University Square to Silvertown. The physical barriers that need to be overcome are the Royal Docks and the City Airport runway.
The design team propose that a bridge will be used to cross the docks and a tunnel will go under the runway.
You can assume ground conditions similar to the site investigation report given in Task 1.
a) You are required to describe and justify the construction methods you propose to build the bridge. Assume for the bridge that piers will be constructed within the dock and the deck will be a series of steel beams with a concrete deck. Use neat labelled sketches to show the sequence of construction.
b) Briefly outline with the use of neat labelled sketches the three following different methods for constructing tunnels:
• Preconstruction & horizontal jacking method
• Cut & cover tunnel
• Bored tunnel
Then select and justify the most appropriate method for the airport tunnel(s).
c) Briefly outline the following dewatering techniques and their application. Then justify the most appropriate methods to help dewater (i) the bridge pier foundations and (ii) the tunnel:
• Sump & pump
• Well-pointing
• Ground freezing
• Compressed air
• Grouting methods