Soil reinforcement:Materials and design questions

- Possible materials for soil reinforcement

Most used:

• STEEL
• POLYMERS (PET, PP, PE-HD, AR, PVA)

- Main design questions:

• What are the soil-reinforcement interaction parameters ?
• What is the long term design strength (TLTDS)of the reinforcement ?

Standards for prefabricated vertical drains (wickdrains)

ISO 12958:1999    Geotextiles and geotextile-related products -- Determination of water flow capacity in their plane
ISO 10319:1993   Geotextiles -- Wide-width tensile test
ISO 11058:1999   Geotextiles and geotextile-related products -- Determination of water permeability characteristics normal to the plane, without load
ISO 12956:1999 Geotextiles and geotextile-related products -- Determination of the characteristic opening size

Below there is a typical datasheet of a wickdrain (prefabricated vertical drain) for soil consolidation. The standards used are listed.

Erosion control - Slopes

Erosion control mat on slopes:

• prevent seeds washed away
• reinforces root system
• repair of heavily eroded areas

Why use PVD over sand drain

Why use PVD (Prefabricated vertical drain) over sand drain

• Installation of PVDs typically 6,000 linear meters per day (depending on the soil and the machine used it changes from 2000 to 8000) and result in a lower project cost.
• No (or less) risk of PVDs breaking during installation - sand drains can have discontinuities if mandril is withdrawn too fast.
• No (or less) risk of shear failure of PVDs during settlement - sand drains are vulnerable to shear failure during settlement.

Extra volume in waste containment

In the construction of waste containments there is an economic advantage of using geosynthetics products.
As seen in the first picture if you use traditional clay and gravel layers in the landfill you can have about 5000 m3 of volume.

But as seen in the second picture if geosynthetics materials are used in the waste disposal area a gain of extra volume will be about 300 m3 with an increase of about 6% in the same area.

Composite drainage for lost shuttering

Some geocomposite drainage products may be used as lost shuttering also.
The drainage composites which have a cement milk-proof layer on one side, made of PVC layer (nonwoven coated with a PP film) could be used for lost shuttering.

Application
1 side PVC geocomposite drains can be used as lost shuttering when installed against the foundation wall of the adjacent building, a bored pile wall, a vertical excavation face or a rock face, permitting to cast the fresh concrete immediately against the drain.