Drainage of structures with geosynthetics
To avoid damage caused by the build-up of hydraulic pressure in retaining walls, bridge foundations, basement walls and other subterranean structures, an effective drainage system is often necessary.
Drainage
Secudrain® is used for the drainage of areas or structures which are in contact with soil, including excavation backfill. It will discharge percolation water, thereby reducing the hydrostatic pressure on the structure and its sealing system. Secudrain® geosynthetic drainage systems consist of a statically stable three-dimensional, wave-structured drainage core, manufactured from polypropylene (PP) monofilaments combined with at least one filter-stable Secutex® non woven geotextile. The polypropylene components are firmly and homogeneously assembled.
Due to the high void ratio of the drainage core (at least 95 %), Secudrain® has a high water discharge capacity in all directions. The relationship between the water discharge capacity and confining stress has been examined in laboratory tests and is documented in pressure-creep-curves. Secudrain® flow capacities are determined based upon the thickness expected under the specific confining stress, which can be correlated to long-term laboratory test results. Therefore, no special reduction factors are required in the drainage calculations.
Filtration
The PP Secutex® nonwoven geo textiles in Secudrain® should be selected in accordance with the filtration guidelines. With proper selection, the geotextile com ponent will prevent clogging of the threedimensional drainage core by fine par ticles while also providing filter stability to the surrounding soil. The physical structure of the three-dimensional, labyrinth-like core, in combination with the Secutex® filter nonwoven maintains the water discharge capacity.
Protection
To protect sealing systems when using coarse-grained drainage soil, mechanically bonded Secutex® nonwoven geotextiles with a mass per unit area of 1,200 g/m² should be installed. For filter stability between drainage soils and fine grained backfill, a filter-stable Secutex® nonwoven geotextile should also be used. When used in conjunction with geosynthetic sealing systems, Secudrain® offers an efficient replacement to mineral drainage layers and filter stabilising geotextiles, whilst also providing protection to the sealing system.
Resistance
Secudrain® and Secutex® products are used for the drainage and filtration of subterranean structures. Carbofol® geomembranes and Bentofix® geosynthetic clay liners are commonly used for the sealing of these structures. All of these products are non-rotting and resistant to typical soil chemicals.
Installation
Secudrain® is quick and easy to fix and install to structures. The flexible, multi-functional drainage material can accommodate corners, edges and complicated geometric structures, without impacting the performance characteristics. The pre-manufactured overlap configuration of Secudrain® provides a simple and quick junction of the panels in the longitudinal direction. This structure ensures the continuous discharge of water within the drainage core. In the transverse direction, the panels are installed with a simple overlap. The standard roll dimension of 0.70 m in diameter (width of 2.0 m and length of 35 m) makes Secudrain® rolls simple to handle and easy to install. For special projects, Secudrain® can be manufactured to a width of 6 m.
Conclusion
Using Secudrain® drainage systems ensures the long-term controlled discharge of percolation water from subterranean structures. Secudrain® drainage systems minimise hydrostatic pressure on sealing systems reducing seepage. When using Carbofol® geomembranes or Bentofix® geosynthetic clay liners, Secudrain® also acts as a protection layer, preventing mechanical damage of the sealing system caused by the backfill material. Even in complicated structures, the use of Secudrain® drainage systems ensures a simple, fast and economical installation.
