Innovative ‘Jumbo’ green terramesh®/Enkagrid PRO design offers developers savings in both materials and construction time

26/11/2004

Maccaferri Ltd, specialist in retaining structures, slope reinforcement and erosion protection, has developed an innovative mesh and grid reinforced slope solution offering significant advantages over more traditional retaining solutions. By combining extended Enkagrid PRO polyester geogrid ‘tails’ within its Jumbo Green Terramesh® units, the company is able to offer developers a reinforced slope solution that conforms to stringent global stability design criteria and is both cost effective and easily constructed.

Maccaferri has recently designed and supplied a 125 metres long Green Terramesh® wall incorporating Enkagrid PRO polyester geogrid to house builder, Redrow Homes (Yorkshire) Ltd, for its Church View development of new homes in Middlewood, Sheffield. The wall is a key element in a programme of groundworks required to stabilise the sloping hilltop site prior to the construction of 118 new homes. Located on a site formerly occupied by a hospital, a retaining wall solution was required to stabilise and extend the area of level ground available for construction.

The order was won following a competitive tender process. The original specification stipulated a timber crib retaining wall, however, Maccaferri was able to demonstrate that the Green Terramesh®/Enkagrid PRO solution could offer significant cost benefits in both materials and construction time, without compromising design criteria for the reinforced slope. Incorporating both mesh and grid within the combined Green Terramesh®/Enkagrid PRO design enabled Maccaferri to offer a solution that could deliver the global stability required, despite the sloping ground and poor soil conditions.

Each Green Terramesh® unit comprises a single sheet of hexagonal, double-twist woven steel mesh formed into three sections to create a 4 metre horizontal soil reinforcement tail, a 0.9 metre facing section and a horizontal return top section. Enkagrid PRO has been used to extend the reinforcement tail to 9 metres. The lower units have been reinforced with an additional layer of Enkagrid PRO inserted at the base and midpoint to ensure a stable platform for construction.

Savings in material costs have been effected with the use of Jumbo Green Terramesh units. Featuring a 0.9 metre facing section rather than the standard 0.6 metre rise, fewer units are required. No temporary formwork is required during construction, integral triangular support brackets behind the front face providing sufficient rigidity for quick and easy installation.

Finally, Green Terramesh® offered an aesthetic advantage over other retaining wall solutions. An in-built layer of biodegradable coir matting provides support for topsoil, encouraging the growth of vegetation as the slope ‘greens up’ naturally. The new residential development is adjacent to woodland and once the grass is established, the reinforced slope will blend in with the environment. The groundworks are now complete and building work is currently underway. When finished, the development will include a mix of two, three and four-bedroom houses and apartments.

Maccaferri Ltd specialises in the supply of gabions, geotextiles, geogrids and geomats. In addition to a full range of products for gabion, timber crib and segmental concrete retaining walls, the company also offers a wide choice of solutions for soil reinforcement and erosion protection, including an in-house design and advice service. Redrow builds more than 4,000 new homes across the UK each year. For more information, call 01924 822566 or visit www.redrow.co.uk.

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