Reinforced Earth 50th Publication

A465 Heads of Valleys Carno Walls

The Heads of Valleys Dualling project is one of the Welsh Government’s key drivers for promoting social and economic regeneration in the area. The new road crosses over the Carno valley on an embankment of earth, this option was selected in place of a viaduct as it would utilise around 250,000 m³ of surplus fill material. To support the new road a multi-tiered Reinforced Earth® retaining wall was designed and supplied by Reinforced Earth Co. Ltd. (RECo). The retaining walls forming the north portal of the underpass are up to 33m high making it the highest structure of it’s type constructed in the UK. The design of the three-tier 33m high retaining walls was technically challenging. The design of this type of structure is not adequately covered by the current design codes and required a significant level of design experience and careful detailing to ensure ease of construction and satisfactory performance. Reinforced soil technology provides an amazingly efficient solution for very high retaining structures. The precast concrete facing panels used have a maximum thickness of 160mm. this offers huge environmental benefit from lower carbon emissions when compared to other solutions such as cast in place reinforced concrete walls. It also reduces the transportation to site by almost 90% providing environmental safety and community benefits.

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