tapis drainant de sable

OBS: Couche drainante: Couche constituée de matériaux perméables mise en place derrière un ouvrage (mur enterré, soutènement) ou sous un ouvrage (radier, dallage, route, barrage) pour faciliter l'écoulement de l'eau du sol et éviter en particulier sa mise en pression. Synonyme : tapis drainant, matelas drainant.

CONT: It has been suggested ... that since the thinnest layer of sand to act successfully as an erosion pumping filter was 25 mm, and the slurry penetrated /3mm in this case, then a geotextile with a thickness of 10 mm or more might successfully replace the sand blanket layer. The fact that the most successful sand blanket have voids ranging from 5 to 30 [micrometers] seems to suggest that the geotextile's voids should be of a similar magnitude. Erosion pumping filters, using a geotextile in conjunction with a sand blanket, are much more effective than geotextiles alone.
OBS: Horizontal drainage blanket: A blanket of pervious material constructed at the foundation from the impervious zone to the landside in a levee or downstream side of an earth dam, to permit the discharge of seepage and to minimize the possibility of piping failure, either of the blowout or subsurface erosion type.