Construction World December 2017


shaping them on site and packing them in a random fashion in the basket. One major advantage of the Terramesh System is its flexibility to cater for settlement and its seismic resilience which offers many benefits to the engineer in the design phase. The full design was carried out by the Maccaferri in-house design department, using Macstars design software. This software, developed in Italy for international use, offers a choice of international design codes in the design package. To satisfy local legislation and construction approval, the design and details were reviewed, cross checked and approved by an Egyptian consultant. The Terramesh unit is manufactured as a continuous horizontal panel of woven steel wire mesh grid with an integral gabion basket facing unit. This makes the design safe, the system efficient and economical to construct. There is no additional complex connection between the grid and the facing unit required. Installation is easy and quicker than other systems and there is less potential risk of error and omission during construction. This is particularly important in the higher sections (above 10 m) where the connection between reinforcing geogrid and facia unit becomes more important to satisfy design codes.

The client is a residential developer, that required a retaining wall of 500 m in length and heights of up to 19 m, running parallel to the shore line of the Red Sea at the resort of Tel Al Ein Sokhna in Egypt.

The wall would function as a vertical structure facing the sea and provide for a flat horizontal surface area in front of luxury villas. It would also facilitate the support of a gantry to access a lift structure that allows villa residents to move from their high vantage point down to sea level. The retaining wall is less than 20 m from the sea with high day time temperatures, coupled with wet and dry cycles of salt spray. The facing had to be durable and strong with a design life of at least 120 years. The Egyptian urban infrastructure uses limestone blocks, for retaining walls and slope protection in a stone pitching or masonry wall application technique. Accordingly, the whole Sokhna development makes extensive use of prepared limestone blocks to create stone masonry slopes and walls as and where required. However, the stone masonry solution becomes expensive when you need to design a 19 m high retaining wall. Additionally, a specialist mason subcontractor had been appointed with a contract to do all the masonry work on the project. The alternative solution had the

restriction that it would need to maintain or keep close to the original scope of the subcontract. The solution required only minor changes in the planning and execution and relatively easy upskilling for the subcontractor. Secondly, no vertical retaining MSEW system in Egypt had been used to such a height before, using only natural materials, so there was no reference. SAMCRETE, the multi skilled contractor now had an opportunity to penetrate the market with a specialist engineering design and solution provider, namely using the Maccaferri Terramesh System which uses Geosynthetic soil reinforcements. Maccaferri Africa based in South Africa was asked to review the conditions and design a suitable solution within the constraints of an existing solution. The solution was the Terremesh System baskets packed with lime stone blocks and using the proprietary Geosynthetics; Paragrid, Paralink and geotextile as building materials. The client decided to choose the most attractive of the limestone blocks to fill the gabion baskets by cutting and


• Company entering: Maccaferri Africa • Designer: Maccaferri Africa from South Africa • Client: Okoplan from Cairo, Egypt

• Contract value: R6,6-million • Start date: September 2016 • End date: July 2017

• Main contractor: Rooye Contractors • Principal agent: Okoplan Consultants • Consulting engineer: Active Brains Consultants

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