Pacific Highway Soft Soil Treatments

Reinforcement, drainage and more for Northern NSW floodplain project

The project

At its inception, the Pacific Highway upgrade was the largest road infrastructure project in Australia. Connecting Sydney and Brisbane, the upgrade began in 2013 and was a major contributor to the country's economic activity.

Construction activity on the Pacific Highway upgrade was officially completed in 2020, and in this case study, we look back at Global Synthetics involvement in this landmark project.

The challenges

The alignment of the highway passes over Northern NSW’s deep, soft soils which are contained within large areas of floodplain. Soft soils were an important design consideration for this project and required special attention from the design team.

Soft soils are characterised by high water content, low capacity for allowing water to pass through, and low strength. Without effective treatment and management, the highway could potentially sink and crack.

A solution that would strengthen and reinforce the soil was required, and the contractors approached the engineering team at Global Synthetics for advice.

Our solution

As part of the design to treat soft soils, engineered materials such as geosynthetics are used to help achieve the intended construction and design requirements.

The engineered materials supplied for this project include ACETex® High Strength reinforcement geotextiles, Ceteau® Prefabricated vertical drains and Geofirma® nonwoven geotextiles.

All of the geosynthetic materials supplied by Global Synthetics have been subjected to independent laboratory testing and rigorous review by the RMS, to ensure that compliance is met in accordance with the related specifications.

Global Synthetics demonstrated they are the technical leader in the market and partner of choice for assisting in the successful design, supply and construction of these geosynthetic solutions.

Global Synthetics supplied large quantities of product for the highway upgrade, including:

• 650,000m2 of ACETex® High Strength Reinforcement Geotextile

• 3,200,000 linear metres of Ceteau® Prefabricated vertical drains

• 2,600,000m2 of Geofirma® nonwoven geotextiles

ACETex® High Strength Reinforcement Geotextile is a polymer-based geotextile that is manufactured specifically for applications of soil reinforcement. It provides high strength up to 12,000kN/m and is proven for use in main roads works and as a treatment for problematic soils.

Ceteau® Vertical wick drains are the most economical ground improvement solution for soft soils with a high clay/silt content. Vertical drains are mostly used to shorten the settlement period of soft, water-saturated soils. When combined with surcharge or vacuum pressure, this can reduce the construction period of a project and avoid post-construction differential settlements.

Geofirma® nonwoven geotextiles are manufactured from the extrusion of fibres which are needle-punched to entangle the fibres and produce a dimensionally stable product. These non-woven geotextiles are generally best suited for a wide range of geotechnical applications involving drainage, filtration, protection and separation.

Find out more about soft soil treatments

Global Synthetics can assist with advice regarding soft soil reinforcement, as well as solutions for embankments, slopes, piles, walls and pavements.

Drawing on our engineering expertise and our range of specialist geosynthetic products, we can provide cost-effective solutions for many different applications.