Brisbane Valley Highway improved with Armormax®

The Problem

The Brisbane Valley Highway passes through the outskirts of Fernvale, west of Brisbane. Along the highway in this area, the eastern batter was showing signs of decay due to the dispersive soils. Dispersive soils are structurally unstable when wet and lack structure when dry, and therefore continued degradation was highly likely without intervention.

An erosion management solution was required, and local engineering consultants GHD sought a solution that would provide both immediate and long-term erosion control.

Our Solution

After discussion with Global Synthetics, the project designer at GHD selected the Propex Armormax® system as an alternative to traditional hard armour. This system comprises a High Performance Turf Reinforcement Mat (HPTRM), in this instance Pyramat® 75, fixed with percussion earth anchors.

Armormax® is engineered to provide long-term design life, with the mat and anchors working together to lock soil in place, resisting movement for permanent vegetated or unvegetated erosion protection.

Pyramat® HPTRM is a synthetic and permanent, UV stabilised product, uniquely designed for severe applications that require outstanding strength and superior vegetation growth. This high-performance turf reinforcement mat is equipped to handle the most demanding erosion control applications.

The product’s patented X3 three-dimensional fibre construction makes this HPTRM significantly stronger than traditional turf reinforcement mats. A resilient ‘pyramid’ weave profile enables more effective reinforcement in challenging conditions such as high flow channels, extreme slopes, stormwater inlets/outlets and similar applications.

Additionally, Pyramat® 75’s outstanding UV resistance means the material can work for over 100 years and makes it the preferred TRM in arid and semi-arid environments where soil reinforcement is needed but full vegetation is not expected.

The Armormax® system incorporates the Pyramat® HPTRM anchored securely in place in this project with earth percussion anchors, a 900mm long anchor field tested to withstand 250kg of pull-out force.

With free EC-Design® Software available from the world leading manufacturer Propex, the system is completely customisable to any individual site, ensuring predictable and lasting performance for the end user.

Armormax® has successfully addressed the surface erosion issues at the site on the steep slope and the engineered anchors have combined to also provide additional slope stability.

The Results

Once installed and vegetated, the batter will have reinforcement for the established vegetation as well as erosion control in place for many years to come.

Images: Timelapse: May 2019, September 2019, November 2020, August 2021

Four Year Review

Four years after the installation was completed the team have carried out a visual inspection. There were no signs of erosion or stability issues anywhere, and the entire site had fully vegetated. This has demonstrated how well the material has performed along with the design and construction.

For more information on this project or to learn more about the products used, please contact our design team at gbs@globalsynthetics.com.au.