Mirafi PET woven geotextiles provide the highest ultimate tensile and long term design strengths (LTDS) when compared to most other geotextiles. Mirafi PET woven geotextiles are comprised of high tenacity polyester yarns with high molecular weight which provide excellent creep resistance, strength and soil interaction.

Mirafi PET woven geotextiles meet the New Zealand Transport (NZTA) clause 6.8.1 of the Bridge Manual 3rd edition, as well as the requirements for all Australian road authorities.

Function

Mirafi PET provides reinforcement, maintaining the stability of soil by carrying tensile loads. It also provides separation, preventing the intermixing of soft foundation soils with granular fill materials, thereby maintaining the structural integrity of the granular fill. 

Applications

Basal Reinforced Embankments

Fine-grained saturated soils exist near most river estuaries and coastal areas around the world. However, these are also areas where infrastructure development, such as road and rail structures, tend to be concentrated most intensely. When constructing over such areas, embankment stability is a major design issue. 

Modern day construction contracts do not permit time for stage construction techniques and land restrictions may not allow berm techniques to be used. Mirafi PET geotextiles are used as basal reinforcement to enable full embankment design heights to be achieved within the contractual period without sacrificing embankment stability.

Basal Reinforced Marine Structures

Sedimentation is a process happening continuously in marine environments. This means that not only such foundations are generally soft but the upper most layers usually contain under-consolidated clay layers. To control stability Mirafi PET geotextiles are used as basal reinforcement to earth-filled platforms, embankments, dykes and breakwaters.

Mirafi PET geotextiles also provide an inward shear restraining force at the soft foundation interface; thereby reducing lateral mud heaves which can be problematic especially if there are adjacent structures sensitive to such movements.

Embankments Over Voids

Foundations that deform differentially when loaded can cause various problems. Examples are foundations with tunnels, voids and isolated soft areas. Localised differential deformations at foundation level can manifest at the surface of the embankment as a depression. Subsidence or collapse can also disrupt buried services.

Mirafi PET geotextiles when laid over such foundations can minimise the risk of foundation subsidence and collapse, and dramatically reduce the negative impact of such occurrences by maintaining serviceability until permanent repairs can be carried out.

Piled Embankments

Embankments and other soil structures constructed over soft and compressible foundations are sometimes designed to be supported by piles. A reinforced concrete capping slab will ensure that the embankment and surcharge load will fully transfer onto the piles.
Mirafi PET geotextiles which can have tensile strengths of over 1,000kN/m, are used as long term design reinforcement to span over the pile caps for the same purpose of load transfer onto the piles, and is a more economical option than the reinforced concrete capping slab solution.

Advantages

  • Improved Stability -  improved stability of embankments, and allows embankment design heights to be achived quickly. 
  • High Strength - With grades from 100kN to 1,600kN.
  • Custom roll lengths can be manufactured to reduce wastage on site.
  • Complies with all ANZ road authority requriements including certificate of conformance requirements.
  • An extremely cost effective construction technique for major infrastructure projects on weak soils.
  • Design support available.
  • Proven performance as used in the most complex infrastructure projects in the world.

Installation

Mirafi PET geotextile should be unrolled in continuous lengths across the embankment as specified by the engineer. Geotextile laps are normally considered to ensure full coverage is maintained even when ground settlements are expected. All protrusions such as tree stumps and rocks should be removed from the site prior to laying Mirafi PET high-strength woven geotextiles.