Mass Gravity Retaining Walls
INANDA - KZN - South Africa
KWAZULU-NATAL DEPARTMENT OF WORKS
INANDA DAM (EAST) ACCESS ROAD
INANDA DAM (EAST) ACCESS ROAD_0
Typical Terramesh™ Unit
Part of the Inanda Dam project included the development of the road infrastructure to access the dam. The geometry of the landscape required fill embankments for the new road surfaces along the mountainous terrain. The remote location of the site added to the costs of importing materials and transportation of plant onto site. The predominant in-situ material consisted of a decomposed granite with a density of 2000kg/m³ making it suitable for the embankment fill. To minimise this fill, a near vertical retaining structure was required along the new embankment. The consultant, Bradford Conning, approached Maccaferri Africa/African Gabions for assistance with the design of four retaining walls with average heights of 3m.
The initial designs by the consultant entailed a conventional mass gravity gabion structure with a large volume of rock – a quantity exceeding that available on site. The Terramesh™ System, consisting of a gabion mesh cage with a continuous mesh tail as reinforcement, was chosen as it required less rock. The final solution consisted of a 7m high Terramesh™ structure with a 2m foundation depth. The mesh tails extended 4 metres into the earth embankment behind the Terramesh™ facing. The Terramesh™ front face consisted of horizontal steps of 220mm and vertical steps of 500mm up to a height of 2m followed by steps of 1,0m. The smaller units at the base reduced bulging and enhanced the stability of the structure.