What is geotextile / prefabricated vertical drains (PVD)?
Many times, the soil integrity for construction sites required for residential, commercial and industrial properties, infrastructure like roads, highways, bridges, railways, airport runways, ports, dock yards, and others is not conducive for building structures. Excessive settlement can take time for soft compressible soils like clay or silt clay with low permeability as they have a lower load bearing capacity.
To strengthen the weak saturated soil and to expedite preconstruction slow draining soil consolidation, a network of prefabricated vertical drains also called as ‘wick drains’ are used for creating drainage pathways into the pore soil. These wick drains are then laid vertically in soft soil with the help of a mandrel/ vibratory hammer /static method that are mounted on a crane or excavator. A surcharge or preloading program is then applied to accelerate the process of soil consolidation and settlement.
The prefabricated vertical drains are made up of a core material, usually of plastic that is wrapped with the spun-bond non-woven geotextiles as an outer layer and acts as a filter fabric. The geotextile filters the soil from entering the water channels and flooding the drain. Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. They have moulded channels that accelerate the soil consolidation process and help to siphon the trapped water in the soft soil strata and bring it to the surface. The duration taken for consolidation of the cohesive soil (sticky soil) depends on the quality of the geotextile, surcharge weight, soft or sand layer of soil and the design and strategic placement (gap between the drains) of the wicks.
In order to determine if a geotextile material is suitable for a particular application it must undergo appropriate mechanical testing procedures. The most common forces a geotextile experiences during its application are tensile and puncture. Each of these forces can cause the premature failure of a geotextile and lead to catastrophic events.
List of our accredited preconstruction soil consolidation test methods
- ASTM D4491 – Permittivity
- ASTM D4533 – Trapezoid tearing strength
- ASTM D4595 – Wide-width tensile strength
- ASTM D4632 – Grab strength
- ASTM D4716 – Discharge flow rate
- ASTM D4751 – Apparent opening size
- ASTM D4833 – Puncture resistance
- ASTM D5199 – Thickness
- ASTM D5261 – Mass per unit
- ISO 9863-1 – Thickness
- ISO 9864 – Mass per unit
- ISO 10319 – Wide-width tensile strength
- ISO 11058 – Permeability
- ISO 11236 – Static puncture test (CBR test)
- ISO 12958 – Water flow capacity
- ISO 13433 – Dynamic perforation test (cone drop test)
Benefits of geotextile and prefabricated vertical drains (PVD)
A well tested good quality Geotextile/Prefabricated Vertical Drains (PVD) installation can have several benefits:
- It improves the permeability of the soil and brings upon faster settlement.
- As the pore water drainage path is shortened, the soil consolidation takes place in weeks instead of years, thus, enabling you to expedite construction and save cost.
- Wicker drains are more economical and cost efficient than prefabricated drains
- Together with surcharge, Geotextile/Prefabricated Vertical Drains (PVD) can considerably reduce the time of soil settlement.
- The installation of Geotextile/Prefabricated Vertical Drains (PVD) is hassle-free and does not take a long time to implement.
- Dewatering of pore water leads to soil improvement in a short period of time.
- Most of the Geotextile/Prefabricated Vertical Drains (PVD) are naturally biodegradable and will not leave any residual plastic.
- Geotextile materials prevent the erosion of earth and similar substances after the area has been altered due to construction usually due to civil engineering applications such as roads, pavement, bridges, embankments and retaining walls.
- The residual settlements are also controlled to a certain extent through Geotextile/Prefabricated Vertical Drains (PVD).
Accreditation and recognition
TÜV SÜD laboratories are accredited to the designated geosynthetic test methods in accordance with the Geosynthetic Accreditation Institute – Laboratory Accreditation (GAI-LAP).
Why choose TÜV SÜD’s geotextile and prefabricated vertical drains (PVD) services?
TÜV SÜD is a trusted, independent third-party solutions provider that carries out impartial analyses and tests of your structures. We carry a variety of tests on Geotextile/Prefabricated Vertical Drains (PVD) to ensure that your preconstruction soil consolidation through wicker drain installation will be conducted in a structured and seamless manner. This will help you mitigate the risk of delay in the project completion and accidents.
Our experts actively participate in the preparation of directives and standards governing safety of engineering structures. This ensures they are familiar with all relevant requirements and regulations. We have decades of international experience in the real estate and infrastructure sector. In addition, we are accredited according to ISO 17020 to conduct independent inspections for quality assurance.