Prefabricated Vertical Drains (PVD)

The vertical drain system has been used since 1930 to accelerate the consolidation settlement process, induced by the pre-loading of normally consolidated low-permeability soil.

By introducing the vertical drains the drainage paths are shortened and, therefore, the time required for excess pore water pressure, induced by the loading operation, to dissipate will be significantly reduced. The depth of drain installation and the applied loads are continuously increasing, which demands a continuous increase in the standards of the vertical drain quality. CeTeau drain is designed for application under the most severe conditions, it has been successfully used for projects where a high drain standard was required.

The advantage of using CeTeau-Drain is that it will reduce the construction time and eliminate of the risk of slip-plane failures.

PVDs are relatively inexpensive, provide high water conductivity and can easily be installed at close spacing, thus shortening the path of the pore water in the impermeable soil and expediting the consolidation process. The graph below shows the effect of PVD in the consolidation process.

Consolidation Principle

Consolidation of compressible soils involves the removal of pore water from the soil. Pore water pressure refers to the pressure of groundwater held within the gaps (pores) between soil particles. The removal of pore water is normally effected by applying a surcharge or preload to the construction area and to squeeze the water out of the soil.

Unfortunately, compressible soils are also often soils with a low-permeability (peat, silt, clays), and as such the water is not easily squeezed out. Without the use of CeTeau-Drain, consolidation settlement in saturated clays can take years, because their hydraulic conductivity is extremely low, and this causes the water to take an exceptionally long time to drain out of the soil. The pore water has to travel through the soil vertically up, or down, to dissipate and it can take decades before a new equilibrium between the effective stress of the soil particles and the pore water pressure is reached. To facilitate the de-watering process, prefabricated vertical drains are installed into the soil, providing a conduit for the water flow. By installing prefabricated vertical drain the excess pore water can flow horizontally to the vertical drain and dissipate vertically through the drain.

Main Application

Vertical drains are mostly used to accelerate the settlement and thus reduce the construction period of a project and avoid post-construction differential settlements. By applying a temporary preload on top of the embankment or fill, the consolidation period can be reduced even more. On top of that, part of the secondary settlement is also eliminated. Especially in peaty soils an extra preload can be very effective.

Special types of vertical drains are developed to meet the requirements for the different applications. CeTeau UK can advise you which type of drain is suitable for your application.

Manufacturing Quality

CeTeau-Drain is manufactured in modern plants in Thailand and Malaysia. It is designed to meet all criteria which are important to achieve a successful and effective consolidation of compressible soils. The synthetic nature of the product makes them suitable for use in the ground where high levels of durability is required. CeTeau drains are manufactured from high-grade polypropylene, this material does not contain any additional chemicals that can pollute the soil. The filter jacket ensures high tensile strength in combination with a low elongation, so that deformation of the drain at high lateral pressure is kept to a minimum. The production facilities in Thailand as well as Malaysia have been certified according to the ISO9001:2008 quality management systems standard by the UKAS-accredited certification bodies AJA Registrars (AJA08/12988) and Global Group (7556213810) respectively. The Thai plant also operates under ISO14001:2004 environmental management systems standard, accredited by AJA’ Registrars certificate No. : AJA13/16511.