Vertical drain technology consists of installing prefabricated drains in the ground, which accelerate the consolidation of impervious soils. Vertical drains are flat, plastic, flexible cables with round or oval cross–section, which, when installed in a suitable spacing, dozens of times increase the permeability of the soil. In order to accelerate the consolidation, together with vertical drainage temporary load embankment is used. Vertical drainage is most commonly used in cohesive soils under road embankments or parking lots.
For projects that can allow time for staged construction, the vertical drain technology can be very efficient and economic. The most common application of this technology is the linear infrastructure such as road or rail embankments. VD technology is also used in tandem with other Menard technologies, for example: Menard Vacuum Consolidation or Dynamic Compaction. Drains treat the soil, greatly accelerating the time of consolidation. The method of vertical drainage is often the only alternative to the implementation of indirect foundation on stilts, especially when in the substrate present are organic soils with high moisture content and thickness in excess of several meters. Drains can reach up to 50m. VD technology can be successfully applied not only to organic soils (peats, aggregate muds, gyttjas), but also to soft cohesive soils (clay).
Depending on the geological conditions and design requirements, the drains spacing is assumed to be from 0.5m to 1.5m. Maximum loads transferred to the consolidated soil (after its draining) depend directly on the type, degree of the consolidation, the nature of the structure and permissible subsidence levels.
- Economy – the main idea of vertical drain technology, that is possibly maximum use of the soil bearing capacity, makes the VD technology one of the most economically beneficial soil improvement methods;
- Environmentally friendly – does not generate vibrations or noise;
- Organically checked – the simplicity of implementation makes this technology efficient for the use in organic soil with high moisture content which has been thoroughly tested in various applications;
- Scale of operation – can be used for low bearing capacity cohesive soils with considerable thickness, even up to a depth of 50 m.