Our soil solution, used at Grootegeluk mine project, offers cost reductions combined with reliability and improved flexibility
The Grootegeluk Medupi Expansion Project required a 12.5m high, 120m long tip wall to be built. This imposed critical design criteria. Our ‘Paramesh’ MSE wall System, which consists of Terramesh® units and ParaLink® geosynthetic soil reinforcement grids, won over all the traditional reinforced concrete solutions on the grounds of cost-effectiveness and the technology’s flexibility.
IMPOSING CRITICAL DESIGN CRITERIA
A more strategic solution for a 12.5m high tip wall able to accommodate 130-tonne CAT 777 tipper trucks carrying coal deposits was required for the design phase of the Grootegeluk Medupi Expansion Project. The job called for very high design criteria to cope with 250 kPa pressure on the wall.
On top of that, the soils utilised in the construction of the wall were on top of coal residue, so corrosion resistance to those harsh soils was needed along with flexibility to withstand any differential settlement.
REINFORCED SOIL BEATS REINFORCED CONCRETE
A traditional cantilever reinforced concrete wall was initially designed. But the costs were so high, we were contacted to come up with a different proposal. Consequently we were able to propose a reinforced soil solution respecting all the original design criteria but this time offering a significant construction cost reduction.
Our in-house MacSTARS W software programme for slope stability, enabled us to design an MSE wall that offered a number of advantages including:
- Flexibility: our ‘Paramesh’ system enables consolidation and settlement without causing any major deformation and without any structural implications.
- Corrosion resistance: with our long-lasting polymer coating we can ensure the wire mesh is protected against degradation from the harsh filling soils and other environmental factors. Also, our high-performance ParaLink® geogrids are among the world’s most tried and tested and offer a 120-year design life along with resistance to chemical, physical and biological conditions that can be found in reinforced soil structures.
- Easy and fast installation: Because Terramesh® units are supplied in standard lengths there is no need for any cuts to be performed on site. This feature not only saves time during installation; but also means that no specialised equipment is required for lifting units into position. All the materials we supply are compacted and are not excessive in weight.
- Environmentally friendly: This sort of soil reinforcement using geogrids allows on-site materials to be reused as structural backfill to the reinforced soil structures, which in turn reduces the environmental impact of importing material and any associated transport costs.
- Local job creation: By installing the Terramesh® units only minimally skilled labour is needed, so contributing to the creation of local jobs.