Maccaferri Middle east provides Terramesh and Geogrid Mechanically Stabilised Earth structure like that used on the CITIC Pacific’s Sino Iron project.
The CITIC Pacific’s Sino Iron project is a world class, large-scale magnetite iron ore project located at Cape Preston, 100km south west of Karratha in Western Australia’s Pilbara region. At the time it was the largest planned magnetite project in Australia. The project has over two billion tons of identified ore and targets exports of more than 27.6 million tones of high-grade iron ore concentrate and pellets each year over its estimated projected mine life of 25 years.
The project features significant investment in dedicated infrastructure including focus processing, pelletizing, a 51 gigalitre desalination plant and port facility, as well as a 450 MW combined cycle gas-fired power station.
As part of the project, four large semi-mobile in-pit crushing stations were required to be installed in the central pit. This involved construction of four primary crusher pockets using sophisticated blasting techniques and up to 24m long soil nails. During development of Pockets #1 and #2, it was identified that the south-west corner geology was not competent enough to carry the proposed design dynamic loads. The truck (600T) turning zone in this area was affected by an adjacent-blast when the permanent batters were created between crusher pockets.
To minimize excavation of the slope and to provide a ‘best-fit’ scenario, a buttress face angle of 63 degrees was selected. It was decided that a combination Terramesh and Geogrid Mechanically Stabilised Earth (MSE) structure would offer an efficient solution, suited to the conditions.
Using Maccaferri Macstars Mechanically Stabilised Earth design software, Geofabrics provided technical support to BGC. This was based on a Maccaferri Terramesh soil reinforcement system with Paralink geogrid primary soil reinforcement, thus creating a ‘reinforced block’.
Paralink is available in strengths up to 1350kN/m. This enables the amount of support in the slope to be optimized regarding location, vertical spacing and required power. Placing fewer layers of a higher strength geogrid allowed a more rapid construction, compared to installing many layers of a lower strength geogrid.
The Maccaferri Terramesh units used in the buttress wall comprise a continuous horizontal panel of woven steel wire mesh geogrid with an integral gabion fascia unit. This makes the system efficient and economical to construct as there is no complex connection between the grid and facial element. Installation is quicker, and there is a less potential risk of errors and omissions during construction.
The fascia unit is filled with hard, rock-fill in the same manner as a gabion and the geogrid tail is then sandwiched between layers of compacted granular fill.
The 2000m2 faced Terramesh structure took around ten weeks to construct including place and compact of backfill.
The project was supplied by Geofabrics Australasia, Maccaferri’s exclusive distributor in Australia.
This technology and service is also available in the Middle East through Maccaferri, with regional offices in Dubai and KSA. The suitability of this solution is also applicable to major infrastructure projects in the Region as it has been tried and tested in similarly demanding environments.
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For further technical information, please download our Case History.