Combigrid® Reinforces the Sălbatica Wind Farm

Combigrid® Reinforces the Sălbatica Wind Farm

Romania | NAUE GmbH & Co. KG

The Sălbatica Wind Farm involved the construction of 35 turbines in the first stage, followed by another 35 in the second stage, each producing 2MW of power. The annual production of the site is 85.5 million kWh/year.

The logistics involved in constructing wind turbines of this size are not simple. The towers are 100m high and built of 5 segments that weigh roughly 65 tons each. For every windmill, eight transport stages are needed: 5 for the pole segments, 1 for the blades, 1 for the nacelle, and 1 for the propeller axle. Erecting them requires heavy cranes. Here, Liebherr 750Tm cranes (roughly 550 tons themselves) were used, assisted by auxiliary cranes of 150, 200 and 500 tons.

Without the aid of reinforcement, just getting the materials and equipment to the proper places on site would be a significant challenge. Site access roads are subject to tremendous loads and must be properly designed and supported.

The existing modulus at the roadway excavation level, for example, was 40-50MPa. This would not be sufficient to support the designed loads.

Romania | NAUE GmbH & Co. KG

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Approximately 40km of access roads were to be constructed and each turbine would require its own crane pad. Roughly 80 truckloads of crushed stone were delivered each day, and each truck carried 35 to 45 tons of aggregate. The design called for roads that could resist 10,000 traffic cycles, and all of the oversized transports meant that additional loads of 65 to 95 tons per truck were regularly rolling across the site. Furthermore, the heavy need for concrete in the turbine/crane pads meant that another 20 to 80 trucks per day (the concrete mixers) were needed.

To maximize access road performance and survivability, engineers specified the installation of 150,000m² of Combigrid® 30/30 Q1 151 GRK 3C reinforcement geogrids. The placement of a 20cm crushed stone 0 to 45mm over Combigrid® produced a modulus of 90-130MPa. The placement of a second 20cm crushed stone layer (0 to 63mm) obtained a modulus of 130-170MPa – more than safe for this design.

The selection of Combigrid® saved the project partners significant time and money while ensuring immediate and long-term safety and quality.