Hull & Humber River Defences Design & Construction of Piled Maritime Walls

Overview

ICE Wales Cymru Ground Engineering Group webinar

The Hull River Defences and Humber Hull Frontages comprise Design & Build flood defence contracts awarded to a BAM Mott MacDonald JV of value approximately £70M, under the Environment Agency’s WEM Lot 4 framework. Severe corrosion of existing sheet piled walls at the low water level threatened to cause widespread collapse of the existing river walls which would impact river navigation as well as increasing flood risk to thousands of properties. The new structures include tied and anchored sheet piled walls as well as 12 cantilever combi walls. The total plan length of piled walls is over 2km and pile lengths are up to 19m. Challenges include very soft ground, works in proximity to fragile structures and tidal conditions.

The presentation will explain the design methodology where there is incentive to start construction at the earliest opportunity despite the need to carry out many surveys to feed into the design. Key aspects of the design include the reduction of cost and carbon by early comparison of tubular and high modulus piles, advanced ground investigation methods to directly assess soil stiffness; and use of finite element analysis to supplement traditional soil-structure interaction, consideration of scour and the durability strategy. Feedback from the construction will include observed ground movements, back-analysis and implementation of contingency plans during land-based installation of piles from behind an old structure.