With the wind energy sector rapidly gaining momentum in Australia and internationally, many more wind farm projects are being built or planned than ever before.
The key to wind farm development often becomes one of access and soil stability. Roads must be built to the giant wind turbine pads, and both the roads and pads must be strong enough to support transportation and long-term siting of those giant turbines.
Due to the size and nature of the turbines, wind farms are usually positioned in low population areas which have low bearing capacity or are otherwise unsuitable for more traditional development. Therefore, due to the low bearing capacity of such areas, and the considerable weight of the construction equipment and turbine components, the construction of strong access roads is critical.
To achieve a long-term, cost-effective and safer solution for these low strength subsoils, geogrid reinforcement is installed between the subsoil and the overlaying base course.
The solution on soft soils
Reinforcement alone is not always enough for construction on soft soils (e.g. subgrade CBR less than 3%). Additional engineering functions such as separation, filtration and drainage will be required in the reinforcement layer. Combigrid® geocomposite combines all of these requirements in a single product. This composite product combines a Secugrid® geogrid with an integrated needle-punched nonwoven geotextile. The geotextile is firmly welded between the reinforcement bars, providing exceptional support for soil stabilisation, separation and filtration applications, in addition to the geogrid’s reinforcement strength.
German made Secugrid® geogrid and Combigrid® geocomposite provide high strength at low strains – an absolute necessity for this type of application. These geogrids possess uniform strength in all of their high-tenacity, flat, welded bars, which creates a rigid, stable, two-dimensional grid that is as strong in its longitudinal direction as in its transverse direction. Additionally, the embossed bars provide frictional performance-improving surface. The end result is superior stress/strain characteristics, especially in the key elongation range (less than 2%).
Combigrid® and Secugrid® provide lateral confinement to the granular material which reduces the lateral and vertical movements of the reinforced layer. This will increase the stiffness of the granular layer and so reduces the required thickness for access roads and working platforms. The high stiffness of these reinforcement products (specially at low elongations) enables them to take tensile loads and control movements immediately.
Combigrid® Reinforced Solutions for Windfarms and Solar Farms
Combigrid® reinforcement provides an excellent cost-effective solution for:
Complementary design software and complete design package is available and can be provided upon request. Please feel free contact us if you are interested and our technical team will contact you accordingly.
More Strength = Less vertical deformation
It is necessary to align the stress/strain behaviour of the installed geogrid to the elongation behaviour of the soil. The performance of the geogrid at a stress/strain ratio in the range of 0.5% and 2% are therefore important, and it is here that Combigrid® shows its strength.
The tensile strength of Secugrid® (Combigrid®’s reinforcement component) is excellent at low elongation. The Secugrid® bars excel at these realistic design levels and show an optimum strength transfer in a design range of less than 2%, demonstrating a high modulus. As the geogrid is much stiffer in tension than the base aggregate, lateral stresses and strains in the reinforced base aggregate are reduced and significantly less vertical deformation can be expected.
The higher the stiffness of geogrid at low elongation (e.g. 0.5% and 2%), the better the performance of the geogrid reinforced layer.
What are the advantages of Combigrid® over woven geotextiles?
There are a number of reasons that geocomposite geogrids such as Combigrid® outperform simple woven geotextiles in high stress applications like wind farm access roads.
Success begins with the individual bars. The tensile performance and dependability of Combigrid® reinforcement is rooted in its flat geogrid bars and how they mobilise high strength at low strain.
Combigrid® and Secugrid® provide reinforcement and lateral confinement through interlocking of the gravel with the geogrid apertures, while the performance of woven geotextiles relies on friction and tension membrane effect which requires some initial movements to be effective.
Independent full-scale laboratory and field studies show higher performance and more allowable traffic passes for Combigrid® reinforced roads compared to woven geotextile stabilised sections. Results available if required.
This interesting short video shows lateral confinement and stability provided by Secugrid® reinforced granular layer:
We provide the complete package
Complete Combigrid® and Secugrid® reinforcement solutions (from design to supply and construction) have been used in various windfarms and solar farms around the world and in Australia and could provide a huge saving to the contractors and project owners.
Please feel free to contact our team for any supply or technical request for your current or upcoming projects or read more about Windfarms.