Design of Geo Textiles:
The factors that control the design and performance of a geotextile filter are:
- Physical properties of the geotextile
- Soil characteristics
- Hydraulic conditions
- External stress conditions.
After a detailed study of research carried out here and in Europe on both conventional and geotextile filters, developed a widely used design procedure for geotextile filters for drainage and permanent erosion-control applications.
The level of design required depends on the critical nature of the project and the severity of the hydraulic and soil conditions. Especially for critical projects, consideration of the risks involved and the consequences of possible failure of the geotextile filter require great care in selecting the appropriate geotextile.
For such projects and for severe hydraulic conditions, very conservative designs are recommended. As the cost of the geotextile is usually a minor part of the total project or system cost, geotextile selection should not be based on the lowest material cost. Also, expenses should not be reduced by eliminating laboratory soil–geotextile performance testing when such testing is recommended by the design procedure. The three design criteria which must be satisfied are
- Soil retention (piping resistance)
- Clogging criteria
For both permeability and clogging, different approaches are recommended for critical/severe applications. Furthermore, laboratory filtration tests must be performed to determine clogging resistance. It is not sufficient to simply rely on retention and permeability to control clogging potential. Finally, mechanical and index property requirements for durability and constructibility are given.
Constructibility is sometimes called survivability, and it depends on the installation conditions. The best geotextile filter design in the world is useless if the geo-textile does not survive the construction operations. have proposed a design procedure based on the pore size distribution of the geotextile filter. Applications Prefabricated Drains In the last few years, prefabricated geocomposite drainage materials have become available as a substitute for conventional drains with and without geotextiles. Geo-composites are probably most practical for lateral drainage situations (c), and (e)] and in waste containment systems in conjunction with clay or geo-membrane liners.
Another important soil improvement application of Drainage applications:
- Trench drains
- Blanket and pavement edge drains
- Structural drains
- Pipe wraps
- Interceptor drains, and
- Drains in dams.