Geotextile and drainage system 1

[nctco]

I have some questions and I hope to get some answer

1- What is the best type of geotextile that can be used in pipe drainage system " woven or non-woven , thickness, density... "

2- Does geotextile " by time and because of fines carried in water" being failed to pass water through to pipes, do fines make clay layer over geotextile?

3- Dose it much better to use weepholes beside using pipe drainage system above footing when we have deep retaining walls " about 20 meters depth"

Finally, can I get drainage system details suitable for my case " retaining walls with 20 m depth" ?

Thanx in advanced

 

[aeoliantexan]

1. Filtration can be accomplished using either woven or non-woven geotextiles with appropriate properties; non-woven materials are more commonly used for this purpose.

2. Yes, fines carried by water can collect on the upstream surface of the geotextile and clog it. Geotextiles are best used against the fine-grained material to hold the particles in place before they become dislodged and begin to move with the water. Most experts recommend against wrapping the geotextile around the perforated pipe because it is likely to clog. Use the geotextile between the cut surface or embankment soil and the clean granular materials.

3. Using properly filtered weep holes as a backup for a pipe drain is advisable, especially for tall walls.

20 m-high retaining walls are expensive and can be dangerous if not properly designed. Your project needs the specific advice of a geotechnical engineer.

 

[nctco]

thank you very much, your answers are very clear and useful.
Actually, the design of the retaining walls mention only weep holes, and while the retaining walls are part of the building block and surrounding four underground floors "used as parking", so I suggested to change the solution to be pipe drain, cause I think it's not good idea to get the water flowing inside the building, that will cause many problem..
That's why I'm looking for the best solution of drainage system that gives enough efficiency without using weep holes.