Embankments are an essential part of the construction of roads, railways, reservoirs, earth dams and other facilities. When constructed in soft soils, ground improvement required to enhance the tension resistance of the soil. Although many studies have demonstrated the suitability of geosynthetic reinforcements, very little information is available on geocell reinforced embankments. This study documents the design, experimental investigation and construction of the geocell foundation for aluminum mine tailing holding pond.
Case study – Red mud pond embankment, India
The study was carried out on the facility enlargement in Lanjighar, Orissa in India. The embankment was part of a red mud pond, used to store the red mud, a waste product from the Bayer process of Alumina recovery. Due to capacity constraint, the embankment height needed to be raised.
Validation – Laboratory tests and analytical study
A laboratory study aimed to ascertain the suitability of the geocell foundation utilized in the embankment. NPA Geocells filled with dry sand were placed on a clay bed and compared to an unreinforced sample. Another sample was further reinforced with a biaxial geogrid. An incremental load was applied to strip footing placed along the width of a cast-iron test tank. The main results are summarized below.
- The NPA Geocell-reinforced sample recorded no clear bearing capacity failure, even up to the large settlement of 45% of footing width, while the unreinforced sample experienced distinct failure.
- Bearing capacity was increased in the NPA Geocell by 4x in comparison to the non-reinforced sample. When further reinforced by a basal geogrid, bearing capacity was increased to 5x.
- In the unreinforced sample, surface heaving was observed. In the case of the NPA Geocell reinforced sample and further reinforced with a basal geogrid, no surface heaving was observed.
The analytical study showed that the combination of NPA Geocell and basal geogrid is aligned with the experimental study. . It not only mobilizes the additional strength in the clay bed but also resists the downward movement of soil due to the footing penetration.
Based on the experimental and analytical studies, the NPA Geocell foundation system was proposed to support the embankment, covering over 15,000 square meters of its base.
Benefits – Robust and cost effective
The newly constructed embankment on NPA Geocell foundation has sustained two monsoon rains and continues to function optimally. No cracks, seepage or settlements have been observed.
- Bearing capacity of the embankment foundation increased by 4-5 times
- Quick solution, with foundation work completed in just 15 days
- Locally available labor and tools used, significantly saving costs