Geosynthetics in roads and pavements

 

Typical Solutions 

The objective of structural drainage is to control 

water pressures and seepage forces in the earth 

adjacent to structures and thus prevent their 

untimely damage, deterioration, or failure. 

 

It has been customary to place a vertical blanket 

of “pervious” sand or gravel behind retaining 

walls for protection against hydrostatic 

pressures.  Yet, it has been demonstrated that 

even when the back face of a wall is drained 

with a vertical blanket significant pore pressures 

can exist in the earth behind the blanket.  This 

leads to increased pressure on the wall.  An 

inclined drainage layer overcomes this 

deficiency by causing seepage to occur in the 

vertical direction. 

 

Still, whether vertical or inclined, a drainage 

layer is difficult to construct using sands and 

gravels.  The drainage layer should be protected 

by a thin filter layer of carefully graded sand 

which is even more difficult, or impossible, to 

place at a steep angle.