Geosynthetics

GEOSYNTHETICS

Geosynthetics are synthetic materials having wide applications in geotechnical engineering. They are fabrics made of nylon, PVC, polypropylene, etc. Geosynthetics last long even if they are buried under the soil. They are not affected by water. Hence, they are used for soil stabilization.

1.  TYPES OF GEOSYNTHETICS

Geotextiles: These are woven or non-woven synthetic fabrics. The fabric may have small holes.

Geogrids: These are made from punching holes in plain polymer sheets followed by two stretching operations. Fig. 1 shows the texture of a typical geogrid.

Geomembranes: They are continuous membranes composed of asphaltic or polymeric materials. They are available with varying permeability. Low-permeability helps to control fluid migration, while high permeability is suitable for drainage.

Geocomposities: They are produced with a combination of geotextiles, geogrids, geomembranes and other materials. The above combination provides optimal performance for a particular application.

2. USES OF GEOSYNTHETICS

The major applications in the field of geosynthetics are the following:

• Geotextiles are used as soil reinforcements to build steep embankments. This saves a lot of space required for approaches to flyovers in cities.

• Reinforced earth walls are more economical in comparison to RCC or masonry retaining walls in forest and hilly areas.

• Geogrid layers are used on weak soil as embankments, instead of replacing weak soil with good soil.

• Plastic geotextile drains are more effective than sand drains for consolidating embankments. Geotextile acts as a separation media but allows water to pass freely.

• Geotextiles are used to provide subsurface drainage so that playing field turf is protected (Fig. 2).

• Geotextiles are used to control erosion in channels, ditches and slopes.