Geonet – Drainage, Filtration, and Landfill Gas Venting

Geonet is a versatile and multifunctional geosynthetic material with many uses. It is most well-known for its ability to help with drainage, filtration, and landfill gas venting.

It has excellent chemical resistance, high strength, and durability. Its grid-like structure enables it to have exceptional hydraulic properties, making it a great choice for many applications.

Drainage

Drainage is a primary function of geonets and geocomposites, allowing water to flow horizontally across the subgrade surface and prevent buildup that can weaken the soil or compromise the structural integrity of pavements and railways. It also helps to stabilize the soil and minimize erosion that can damage infrastructure, contaminate waterways and ecosystems, and cost more to repair or replace.

To ensure that drainage functions are effective, Geonet/geocomposites are manufactured with a high in-plane hydraulic flow rate, or transmissivity value. This measurement is based on a series of physical, mechanical and endurance tests that are covered in ASTM, ISO and GRI standards.

Geonet/geocomposites are typically extruded from high-density polyethylene or polypropylene to maintain a constant thickness, providing long-term durability and resistance to degradation from UV exposure and weathering. This longevity helps to reduce installation costs, and minimize the need for maintenance and replacement over time.

The structure of the ribs in geonets and geocomposites allow for an efficient drainage system by facilitating water flow across the entire surface. This is especially important for landfill leachate collection, foundation wall drainage and methane gas collection, as well as highway and roadway drainage. Geonets can be used alone or in combination with geotextiles to provide a complete drainage system. They are also ideal for slope protection and retaining walls, as they can help distribute loads evenly to prevent landslides or soil subsidence.

Reinforcement

Drainage: Geonets facilitate drainage, preventing the buildup of hydrostatic pressure in the subgrade and reducing the risk of water-induced damage such as erosion or soil instability. This function is particularly important in pavement structures and railways where the subgrade is under continuous heavy traffic loads.

Soil Reinforcement

Besides facilitating drainage, Geonets can also reinforce soil and improve its strength and load-bearing capacity. The ribs on the surface of the Geonet can distribute Geonet the load over a wider area, thereby improving the soil’s stability and limiting deformation and settlement.

Erosion Control

The erosion-control function of Geonets is especially important in slopes and embankments. Unlike geotextile, which only limits the movement of soil particles, geonets can actually reinforce and stabilize the soil, which makes it less prone to erosion. Geonets can be used to construct erosion-control walls, stabilize embankments and improve the performance of roads.

A study conducted on Hall’s Creek test embankment constructed on an alluvium deposit in Moncton and a reinforced test embankment constructed on a soft compressible clay in Sackville shows that the behavior of the soil improved after geotextile reinforcement was introduced. This improvement was attributed to the fact that the addition of a single layer of Geonet reduced resilient and permanent deformations, and increased soil-geonet interface resistance. Extensive laboratory testing and finite element numerical modeling were carried out on various configurations of the footing (shape and size), the number of geonet layers, length, depth of the first layer, and spacing.

Erosion Control

Unlike traditional drainage and filtration materials, geonets are durable, chemically inert, and resistant to degradation from sunlight, moisture, and biological factors. This durability and longevity help minimize maintenance and replacement costs over a project’s lifespan.

Geonets have a grid-like structure that allows for the efficient flow of water and other liquids while retaining soil particles to prevent clogging. They are typically made of synthetic polymers such as high-density polyethylene (HDPE) or polypropylene and can be manufactured in a variety of dimensions and thicknesses. Depending on the application, some geonets have filtering properties, allowing them to trap fine particles while still facilitating water movement.

When used in combination with geotextiles, geonets also contribute to soil stabilization and slope erosion control. Their structure helps distribute loads evenly, reducing stress on underlying materials and increasing the lifespan of engineering projects.

For applications requiring enhanced drainage and filtration, some geonets are designed to have larger openings in their ribbed or channel structures to allow for increased hydraulic transmissivity without clogging. Biplanar geonets are often used for this purpose, as they have two sets of ribs oriented at an angle to provide improved drainage and filtration capabilities. Some are also available with a non-woven needle-punched geotextile laminated to one or both sides to prevent soil particles from clogging the drainage core. Other options include triplanar and boxlike channels that are designed to have high transmissivity in both machine and cross-machine directions.

Applications

Modern geosynthetics have been successfully used in various areas of construction. This is due to the fact that these materials can withstand considerable pressure. This is a critical aspect, especially in landfill cells where the structures must be able to hold a large amount of liquids and gases. This is also important in tunnel drainage where high loads must geotextile fabric suppliers be able to pass through the material without compromising the structural integrity of the tunnel walls.

In addition, geonets are also designed to facilitate drainage in road and railway construction, earth retaining structures, and drainage layers in ponds and reservoirs. They do this by providing a pathway for water to move through them, thus alleviating hydrostatic pressure and preventing soil clogging.

Another important function of geonets is their ability to provide reinforcement and enhance the stability of soil structures. This is because they have a grid-like structure with regular openings that interlock with the surrounding soil. This increases the shear strength of soil structures and helps to distribute load more evenly, thereby reducing the risk of subsidence.

In addition, geonets are used in a number of applications that require drainage, gas venting, and erosion control. These include landfill leachate collection, tunnel drainage, roadbed enhancement, and slope protection. They also play a vital role in enhancing the safety of slopes and embankments in mining operations. Additionally, they can be used in landscaping to reduce water runoff and promote vegetation growth.