How geogrid works

Below a video simply shows how geogrid works.

Ofcourse there are a lot of things to do for design and applications but this video simply explains the supporting power of geogrids.

Take a box and fill it with gravel.
Somebody step on gravel.
The gravel does not hold the person up.
Then reinforce the gravel with geogrid layers.
Next when you remove the box, you can see that system is supported by the geogrid layers.

Soil reinforcement:Materials and design questions

- Possible materials for soil reinforcement

Most used:

• STEEL
• POLYMERS (PET, PP, PE-HD, AR, PVA)

- Main design questions:

• What are the soil-reinforcement interaction parameters ?
• What is the long term design strength (TLTDS)of the reinforcement ?

Advantages of using uniaxial geogrids in reinforced soil retaining walls

Advantages of using uniaxial geogrids in reinforced soil retaining walls, can be listed as follows:

• Fast construction in all weather conditions
• No mortar, dry built
• Optimal utilization of land
• Free design support (almost all the companies supply)
• Aesthetics: impressive & stylish designs
• Versatility & flexibility
• Cost efficiency
• Durability, resistance to environmental influences
• Accredited by independent testing laboratories
• Minimal maintenance

Multifunctional geogrids

• grid embedded in nonwoven filter layers
• One-step easy installation
• Optimal interaction with the sub-grade
• High modulus, low strain (Enkagrid TRC)
• Geogrid and nonwoven geotextile together

Functions:
Stabilization+ Filtration+ Separation

Geogrid in railways

Uniaxial geogrids were applied in this railroad project between Aliaga-Izmir cities.

Geogrids were installed as several layers and the specially chosen soil between the layers was compacted. Like the roads in railroad backfills uniaxial geogrids can be used.

Applications of biaxial geogrids

Applications of biaxial geogrids

• Structural foundations
• Paved roads
• Construction haul roads
• Permanent unpaved roads
• Airport runways
• Car parks
• Basal reinforced platforms

Applications of uniaxial geogrids

Some Applications of uniaxial geogrids

• Bridge abutments
• Steep slopes
• Walls
• Embankments
• Segmental retaining walls
• Landfill capping
• Landfill foundation
• Topsoil stabilization
• Structures over mining areas

Main geogrid types depending on functions

Geogrids can be produced as :

• Uniaxial geogrids
• Biaxial geogrids
• Multifunctional geogrids

Reinforcement of silo foundation

The project contains the foundation of 4 silos with a diameter of 27 m each, to be used for the storage of grain. The soil had insufficient bearing capacity to prevent differential settlements under the circular loaded area.
The steel wall of the silo was placed upon a concrete foundation. The bottom of the silo consists of a circular concrete plate which is not connected to the surrounding foundation of the wall.
When the silo is filled, this could bring about some movement of the plate caused by the consolidation of the subgrade. A local designer made a design with four layers of Enkagrid TRC-20 geogrid to improve the bearing capacity of the foundation underneath the silos.
TRC-Grid reinforces the granular fill and prevents mixing of the particles of the subgrade and the granular fill during the design life.
Furthermore TRC-Grid acts as a filter around the drainage pipe. Differential settlements can occur due to consolidation or loss of bearing capacity of the underlying subsoil between the silo wall and the silo bottom plate. However, the support and the movement of the silo bottom plate should be uniform.

Geogrid with a filter layer

Kocaeli free zone project has a harbour inside the project. There is a heavy traffic of trucks. To prevent or reduce partial settlements on the roads due to the heavy truck traffic special geogrid was used.

This multifunctional geogrid delivers reinforcement, separation and filtration in one easy-install product for paved roads, parking areas, platforms and building/structure foundations. In the project it reduced the required subbase thickness.

Due to the special manufacturing method Enkagrid TRC has very low elongation properties.

It helps to reduce the partial settlements.

Beside the reinforcing Trc geogrid also provides a filter layer. So it works like a geogrid and a nonwoven .

This type of geogrids work as reinforcement, separation and filtration layers.

Reinforcement of roads by geogrids

On weak soils, for road construction contractors generally need a thick layer of base course.

Using geogrids as reinforcing layers can help to reduce the required thickness of the unbound base course stabilizing structures on soft ground or in unsettled areas.

Another problem is the forces coming from the traffic causes crack on the surface of the road. Geogrid reinforcing layers can absorb the forces and delay propagation of cracks the life of the structure may be increased.

In railway construction multiple layers of geogrid reinforcements can be used to provide more effective stabilization.

Geosynthetics

We can simply devide geosynthetics in below groups.

1)Geotextiles:

• Woven fabrics
• Geogrids
• Nonwoven fabrics (Thermally, mechanically, chemically bonded)
• Nets
• three dimensional mats

2)Geomembranes:

• HDPE , LDPE liners

3)Geosynthetics clay liners, (bentonite mats)

4)Geocomposites

Geocomposites are made by using above product with each other. For example a drainage composite can be made by joining 2 filter fabrics (nonwovens) and a 3 dimensional mats in the middle.