Performance of shallow footing on geocell reinforced clay bed using experimental and numerical studies, Hegde and Sitharam (2012)

Construction in soft, weak ground requires treating large areas to a greater depth to ensure the safety of the superstructure. Usually, deep foundation techniques or ground improvement techniques are applied. However, this usually proves to be very costly. Past research has demonstrated that geocell reinforcement increases the load carrying capacity of the foundation bed. It is also a cost-effective solution.

However, very few researchers have directly used a commercially available geocell, such as NPA Geocell in their studies. Such a study is especially relevant as these are the geocells which are directly utilized in soft soil.

Validation – Laboratory tests and numerical simulation

In a laboratory model plate load test, NPA Geocell was placed upon a foundation bed and filled with sand. A load was then transferred to the footing. Deformations to the soil were measured with dial gauges. This was compared with the same tests on an unreinforced sample. The main results are summarized below.

  • The geocell-reinforced sample recorded no clear bearing capacity failure, while in the unreinforced sample, the slope of the pressure settlement curve becomes nearly perpendicular beyond a settlement about 20% of the footing width.
  • When the clay surface started heaving, the geocell reinforcement added strength and stiffness in the clay bed and allowed it to continue to take up the additional loading.
  • Bearing pressure was further increased by an additional planar geogrid at the base of the geocell. NPA Geocell reinforcement by itself increased load carrying capacity of the foundation bed by 5 increments. This increased to 6 increments with the addition of the geogrid.

A numerical simulation was also carried out, using FLAC software, in order to further verify the findings. The numerical results were found to be similar to those of the laboratory experiment.

Benefits – Increased load carrying

The results demonstrate that reinforcement with NPA Geocell significantly increases load carrying capacity of soft clay, especially when a planar geogrid is added. It is therefore a recommended pavement solution for soft subgrades.

  • Increases load carrying capacity x 5, reaching x 6 when geogrid added
  • Longer lasting paving solution in comparison to deep foundation or ground improvement techniques
  • A cost effective paving solution in comparison to deep foundation or ground improvement techniques

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