Neoloy Reinforcement for Mine Waste Containment
Neoloy® Tough-Cells were chosen to strengthen the foundation of unconsolidated mud embankment for mine waste management
The Vedanta Aluminum company needed to increase the storage capacity of alkaline red mud (a waste/by-product of alumina processing) in open air ponds/ dykes constructed from unconsolidated red mud slurry. The goal was to strengthen the foundation of the 15,000 sq m embankment to support a 3m high addition to the earthen dyke.
The goal was to strengthen the foundation of the 15,000 sq m embankment to support a 3m high addition to the earthen dyke.
The senior design engineering consultant, Dr. T.G. Sitharam (Chairman, Centre for infrastructure and Sustainable Transportation & Urban Planning – CiSTUP), Indian Institute of Science (IISc), Bangalore, chose the Neoloy Tough-Cell solution after experimental and analytical modeling.
Lateral confinement by Neoloy Tough-Cells transfers vertical loads horizontally, while the reinforcing mechanism creates a stiff geocell mattress. This stabilizes the footing of the embankment, reduces settlement and prevents slope failure. The proven durability of the Neoloy polymeric alloy used in the geocells to withstand large stresses in a harsh chemical environment over time gave a high degree of confidence to the solution.
Alternative solutions called for sand/stone columns and pre-vertical drains along the depth and base width of the dyke. These techniques are too difficult in the presence of water, required the import of sophisticated earth machinery to a very remote site, and would be a very complex and expensive solution.
Neoloy Tough-Cell Solution
356 Neoloy Tough-Cells 10 cm in height were placed below the footing with a thin layer of sand layer to reduce settlement. A planar geogrid was installed at the base of the geocell mattress, which acts as a membrane, to improve the bearing capacity (after water was drained out). Free draining material at the base avoids direct contact with the foundation and accelerates consolidation of the underlying soft clay. Good quality murrum soil (granular sand, gravel) was used for infill, compacted to the required density.
Neoloy reinforcement contains and confines the shearing soil mass just below the foundation of the proposed dyke (footing). This transmits the footing pressure laterally and gives rise to higher load carrying capacity. Slope stability was confirmed by analysis.
See recently published articles by Sitharam and Hegde (2013, 2012) providing in-depth analysis of the project:
- Design and Construction of Geocell Foundation to Support the Embankment on Settled Red Mud
- Performance of Shallow Footing on Geocell Reinforced Clay Bed using Experimental and Numerical Studies
- Fast installation –completed in 15 days using locally available labor and construction equipment in a very remote area.
- Performance – embankment withstood monsoon rains with no deterioration.
- Cost-effective –much lower cost than engineered alternatives.
- Sustainable –locally available murrum soil was used for infill instead of importing high-quality granular materials.
- Multiple use – same Neoloy Tough-Cells used for slope and geomembrane protection, load support and retention walls.