geosynthetics.pptx (Size: 5.09 MB / Downloads: 330)
Geosynthetics – a planar product manufactured from polymeric materials used with rock, earth, or other geotechnical engineering related material as an integral part of a human-made project, structure, or system.
“GEOSYNTHETICS ARE NEW BUT THE CONCEPT IS NOT”
Use of geosynthetics in field (PICTURES)
The term ‘Geosynthetics’ has two parts: the prefix ‘geo’, referring to an end use associated with improving the performance of civil engineering works involving earth/ground/soil and the suffix ‘synthetics’, referring to the fact that the materials are almost exclusively from man-made products. The materials used in the manufacture of geosynthetics are primarily synthetic polymers generally derived from crude petroleum oils; although rubber, fiberglass, and other materials are also sometimes used for manufacturing geosynthetics.
Geosynthetics are usually sheet materials supplied in roll form and they are used in many geotechnical applications.
There are five categories - geogrids, geomembranes, geonets, geotextiles and related products (materials such as erosion mats) that do not fall naturally into one of the other four categories.
There are six main functions that these materials can provide and many products provide one of more of these, particularly the geocomposites which, as the name suggests, are made up of multiple components.
Roles of geosynthetics :
Preventing intermixing of soil types
or soil/aggregate to maintain the
integrity of each material yet still
allow the free passage of
liquids/gases. Commonly used in
between sub-base/subgrade and
around drainage materials.
A geogrid produced by the longitudinal stretching of a regularly punched polymer sheet, and therefore it possesses a much higher tensile strength in the longitudinal direction than the tensile strength in the transverse direction.
A geogrid produced by stretching in both the longitudinal and the
transverse directions of a regularly punched polymer sheet, and therefore it possesses equal tensile strength in both the longitudinal and the transverse directions.
It is a planar, polymeric product consisting of a regular dense network of
integrally connected parallel sets of ribs overlying similar sets at various angles. At first glance, geonets appear similar to geogrids; however, geonets are different from geogrids, not mainly in the material or their configuration but in their functions to perform the in-plane drainage of liquids or gases.
It is a planar, relatively impermeable, synthetic sheet manufactured from materials of low permeability to control fluid migration in a project as a barrier or liner. The materials may be polymeric or asphaltic or a combination thereof. The term barrier applies when the geomembrane is used inside an earth mass. The term liner is usually reserved for the cases where the geomembrane is used as an interface or a surface revetment.
Mainly used for:
Water conservation projects (Agricultural ponds, Fire water holding ponds, Raw water reservoir or lakes, etc.)
Water transport projects (Canal lining, Drainage lining, Embakment protection liner, etc.)
Water treatment projects
Land fill projects
It is a term applied to the product that is assembled or manufactured in laminated or composite form from two or more materials, of which one at least is a geosynthetic (geotextile, geogrid, geonet, geomembrane, or any other type), which, in combination, performs specific function(s) more effectively than when used separately .
There are a number of geosynthetics available today, including webs, grids, nets, meshes, and composites, which are technically not textiles; however, they are used in combination with or in place of geotextiles. All such products are often called geotextilerelated products (GTP). Some common GTP and other types of geosynthetics are briefly described below.
A three-dimensional, permeable, polymeric honeycomb or web structure, assembled from geogrids and special bodkins couplings in triangular or square cells or produced in the factory using strips of needle-punched polyester or solid
high density polyethylene (HDPE).
A polymeric material manufactured by the application of the polymer in semi-liquid form through the use of a foaming agent to have a lightweight material in slab or block form with high void content for use as lightweight fills, thermal insulators and drainage channels.
Geomat: A three-dimensional, permeable, polymeric structure made of coarse and rigid filaments bonded at their junctions used to reinforce roots of vegetation such as grass and small plants and extend the erosion control limits of vegetation for permanent installation.
Geomesh: A geosynthetic or geonatural generally with a planar woven structure having large pore sizes, which vary from several millimetres to several centimetres for use in mainly erosion control works .