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geosynthetic definition: The word geosynthetic consists of two parts: Geo and Synthetic. The word Geo is used where it refers to the ground, and synthetic is used where it is made of man-made material. Geosynthetic reinforced soil refers to products that solve geotechnical and soil problems. Some of the products that are called Geosynthetic reinforced soil are:

  • Geotextile
  • Geogrid
  • Geomembrane
  • Geonet
  • GCL or geosynthetic clay liner
  • Geofoam
  • Geocell
  • Geocomposite
Different types of geosynthetics for soil reinforcement
Different types of geosynthetics for soil reinforcement

Different types of geosynthetic Reinforced Soil
Different types of geosynthetic Reinforced Soil

The polymeric nature of the mentioned products makes them very durable. Geosynthetics are used in different forms and different geotechnical, transportation, environmental and hydraulic applications in the following cases:

Roads, airports, railways, earthen dams, environmental, water storage pools, dams, canals, erosion control, sediment control, landfills bedding, landfills cover, mines, aquaculture and agriculture

When geosynthetics are used in contact with soil, rock or any other engineering material, one or more of the following functions are always expected:

  • Reinforcement
  • Separation
  • Filtration
  • Drainage
  • Dewatering
  • Protection
Different applications of geosynthetic Reinforced Soil
Different applications of geosynthetic Reinforced Soil

History of geosynthetic Reinforced soil method

The use of geosynthetic reinforced soil dates back to thousands of years ago, the time of the ancient Romans. They used geosynthetic reinforced soil method to build roads and their edges. This type of primary geosynthetic soil is made from a combination of soil with natural fibers, fabrics or plants.

As the polymer industry developed, so did geosynthetics, until the International Geosynthetics Society (IGS) was formed in 1983 in Paris. The earliest attempts to strengthen the soil were to use the foliage of trees in swamps and sand dunes, but today, geosynthetic reinforced soil was first used in the United States in the late 1940s and early 1950s and has popular in Europe in the 1970s. Recently, the use of these materials has become common in Asian countries.

In Iran, after more than a decade of extensive activity, a large number of engineers in the form of contractors, consultant engineers, commercial companies and real personalities in order to develop geosynthetic engineering in Iran and in line with the measures previously taken to set up a public organization (NGOs and without commercial affiliation), the Iranian Geosynthetic Engineering Association (www.iranigs.com) was founded in its current format, from the fall of 2007.

Types of geosynthetic reinforced soil

Geosynthetics are divided into several general groups:

  1. Geotextiles: Geotextiles are permeable textiles that can separate, filter, strengthen, protect or drain when used with soil. Geotextiles are used in various fields:
Geotextile
Geotextile

  • Drainage
  • Protection
  • Erosion control
  • Separation
  • Filtration
  • Reinforcement

Examples of geotextile applications are reinforcement, separation, proper drainage, increasing the bearing capacity of asphalt and soil, increasing the useful life of asphalt, structural protection of beaches and ports, homogeneous subsidence in offshore structures such as breakwaters, ground protection in erosion, protection of ballast layer in railways, increase of bearing capacity of the road and railway bed, protection of geomembrane layers.

2) Geogrids: Geogrids are used to reinforce and stabilize the soil. Geogrid is a mesh plate that has more locking properties compared to geotextiles, ie it is involved with soil particles and gives high longitudinal and transverse resistance to its substrate. This product is mostly used in retaining walls and road construction and is produced from materials such as polyethylene, polyester, fiberglass and with different properties.

Geogrid
Geogrid

3) Geomembranes: Geomembranes are sheets of polyethylene, PVC, etc. that are impermeable to a variety of fluids (eg water, chemicals and petroleum). Geomembranes are used for dewatering, construction of artificial lakes, fish ponds and industrial ponds, sewage lagoons and water and sewage pipes. Geomembranes can be installed alone or with a variety of coatings, such as concrete plates or debris. Among the applications of this product are:

  • Improving the quality of old dams
  • Isolation
  • Preventing leaks in the bottom of tanks
 Geomembrane
Geomembrane

                                                                       

The life of uncoated geomembranes is slightly shorter than that of coated geomembranes because they are exposed to ultraviolet rays, but on the contrary, they are easier to repair than coated ones. On the other hand, coated geomembranes are more at risk of perforation. Geotextiles are usually placed below and above the geomembrane to protect it from perforation. It also strengthens the bearing capacity of the structure and geomembrane. In this case, the geotextile acts as a shock absorber that reduces the concentration of pressure on the geomembrane layer.

4) Geonets: Geonets are suitable for preventing slope erosion and drainage. The distance between the strands of this type of geosynthetic has created very good conditions for use in drainage operations. In this way, geonets are available with different pore sizes and according to the size of soil particles, they are selected in such a way that they can drain due to the displacement of soil particles. Hence, the main function of geonet is drainage. However, due to the lower price of geotextiles for drainage, geotextiles have more applications than geonets.

Geonet
Geonet

Geonets for preventing slope erosion and drainage
Geonets for preventing slope erosion and drainage

5) Geocomposites: A combination of different geosynthetic sheets has been made such as:

  • Geotextile – Geonet
  • Geotextile – Geogrid
  • Geotextile – Geocell

And in many cases they are used as drainage filters. Popular types are commonly used to drain sports fields and retaining walls and tunnel ceilings.

Geocomposite
Geocomposite

6) Geosynthetic clay liners (GCL): Geosynthetic clay liners or GCL according to the definition of geocomposite, is a type of geocomposite, but due to its wide application and similar function, geomembranes are considered separately and consist of geosynthetic sheets with interlayers of clay (bentonite) and are used to prevent water leakage and dewatering. The common type consists of a layer of bentonite between two sheets of geotextile or between a layer of geotextile and geomembranes. The special advantage of Geosynthetic clay liners (GCL) is its self-healing and fusion properties.

Geosynthetic clay liners (GCL)
Geosynthetic clay liners (GCL)

7) Geocells: Geocells are used to stabilize slopes. The geocell is made of heavy ethylene and has a structure similar to a honeycomb. The main application of Geocell is:

  • Solving soil maintenance problems
  • Soil stability
  • Controlling soil erosion

8) Geofoams: Geofoams are produced from polymeric materials or a combination of minerals. Due to the ability to withstand pressure, seismic shock absorbers, reducing the effect of inflationary pressure created by expanding soils, reducing the weight of the embankment in lightening, stabilizing slopes, protecting buried pipes and underground structures, and so on, they are used in various construction projects for significant benefit.

Geofoams
Geofoams

Design basics of geosynthetic Reinforced soil

The design of geosynthetic reinforced soil walls is conventionally done using simplified and classical analyzes or experimental methods.

The geosynthetic reinforced soil execution method

An Embankment in geosynthetic reinforced soil structures is carried out in layers and are compacted similar to conventional embankments. The reinforcing members are located in the space between these layers.

Advantages of geosynthetic reinforced soil

Few civil engineering basins can be named that have witnessed such growth and development in a short time. There are many reasons for this huge growth, including the following:

  • Occupying less space
  • Material quality control in the factory
  • Proper price
  • High speed execution
  • Ease of execution
  • Abundance of materials
  • Reducing the use of natural resources
  • No rust
  • High resistance to biodegradation and chemical decomposition
  • Long-term reliability after being buried in the soil
  • High flexibility
  • Very small volume
  • Lightness
  • Ease of transportation and storage
  • Creating a beautiful appearance for structures
Some advantages of geosynthetic reinforced soil
Some advantages of geosynthetic reinforced soil

Related contents:

Federal Highway Administration (FHWA)

Geosynthetic-Institute

Iagi , Geosynthetics Installers

Intlining , INSTALLATIONS

Yzleebo , Stitchbond And Geo Product

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