Geogrid for stabilisation at Stags Holt Wind Farm

Geogrid for ground stabilisation at Stags Holt Wind Farm

PRODUCTS:

TENAX LBO geogrids

Location - Date:

Stags Holt Wind Farm, Cambridgeshire, UK - 2008

Distributor:

Geosynthetics UK

Project description

The Stags Holt windcluster project is an 18MW wind energy project at Stags Holt near March in Cambridgeshire, UK.

Once complete, the nine-turbine project will be able to supply the electricity needs of approximately 9500 homes.

The Stags Holt windcluster would be expected to have an operational life of approximately 25 years.

After this time, the development would be decommissioned in order to return the site to its former use as arable land.

The construction of the windcluster would be completed within a period of approximately 30 weeks.

Challenge

The 80 m diameter wind turbine blades at Stags Holt are mounted on 59 m high towers. Each turbine would be accessed by approximately 8 km of internal access tracks that would be approximately 5 metres wide, with areas of hardstanding adjacent to each turbine for use by cranes during construction.

The tracks and hardstanding areas, which mainly utilise soft existing farm tracks, would need reinforcing so that they were able to withstand the loads generated by the cranes during the commissioning and decommissioning of the turbines.

Solution

Geosynthetics worked together with the Tenax Geosynthetics Technical Office to produce the designs for the site access roads which incorporated the use of two layers of lime cement stabilisation followed by the installation of a 200 mm of Type 1 road stone reinforced by a single layer of TENAX LBO 330 bi-oriented geogrid.

The designs ensured:

The site access road would be strong enough to withstand loadings of the wind turbines and heavy vehicle usage for the duration of the site (25 years);
A reduction in costs of fill material required (up to 40%);
A reduction on the environmental impact of construction traffic that would be mitigated due to the reduced quantities of aggregate required.

Geogrid for ground stabilisation at Stags Holt Wind Farm

Stags Holt windcluster project

superficial structural foudnations

Benefits of using bi-oriented geogrids in road bases

Horizontal layers of geogrid are commonly used to reinforce the base of road structures on soft soils with poor bearing capacity and reduce settlements that could occur under the distributed load transmitted by the passage of the construction vehicles.

The presence of the geogrid has the effect of distributing the loads and therefore reducing stress concentration over the soil thereby minimising differential settlements.

The reinforcement function provided by the geogrid consists of many different factors; some of the most important contributions are:

Increase in initial stiffness;
Decrease in long-term deformation (creep);
Increase in tensile strength;
Reduction of cracking;
Increase in soil subgrade strength;
Improved load distribution to the soil subgrade due to the load spreading.

Using TENAX LBO 330 provided a solution that would maximise the sustainability of the site whilst reducing costs and minimising environmental impact.

Download:

Geogrid for ground stabilisation at Stags Holt Wind Farm, Cambridgeshire, UK

Applications:

Superficial structural foundations