Cofferdam Solution for Crossrail

Tony Gee has designed a revolutionary tubular piled cofferdam solution for the new Canary Wharf station. The new station box is the first construction project to start on the £15.9 billion Crossrail scheme. The 18 metre deep cofferdam wall is being installed by Giken, on behalf of Expanded Ltd, in 10 m of water in North Quay.

Expanded Ltd engaged Tony Gee to design a watertight interlock and to determine a safe push-in force for the tubular piles. The solution was required to prevent damage and loss of interlock during installation and under conditions where the wall undergoes lateral deflection, caused by dewatering and excavation of the dock.

The design process necessitated a structural assessment on the forces that could be carried safely at the base of the tube and interlock. Back-analyses of preliminary pile trials helped to calibrate our non-linear finite element modelling in a 3D PLAXIS analysis. Tony Gee’s computational ground modelling capability has been proven to be a articularly powerful tool in predicting ground movements on other London railway schemes such as High Speed 1 Phase 2.

July 2010

Canary Wharf Station

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