Moreton Bay Rail Link – Access Roads and Working Platforms
The $1.15 billion Moreton Bay Rail Link project will run from Petrie to Kippa Ring and is one of the mostly highly anticipated infrastructure projects in southeast Queensland.
The access roads and working platforms had to be built on a very soft soil (Cu=6 kPa) and withstand very heavy loads. The project could not tolerate platform thicknesses in excess of 1m. The consultant was looking for an economical solution to overcome these problems.
The Final Solution
After several investigations, the geogrid reinforced platform was considered as the suitable solution. The initial design was 124cm reinforced platform with 3 layers of geogrid. The designer undertook further detailed design and sensitivity assessments using a range of techniques and products. The design was then reduced to a 100cm thick platform using one layer of Combigrid® geocomposite and two layers of Secugrid® geogrid. Large scale load testing was completed along the platform to verify the final design.
Combigrid® is the combination of Secugrid® geogrid and an integral nonwoven geotextile. This geocomposite is suitable for construction on soft soils where both geogrid and geotextile are required. Combigrid® saves construction costs and time by having the benefits of two products all in one product.
The plate load test results during and after the platform construction showed very good performance and verified the success of the design with Combigrid® and Secugrid®. The high stiffness and performance properties of Secugrid® and Combigrid® led to a more economical reinforced design compare to other reinforced solutions and materials.