Soil erosion from wind and rainwater runoff was plaguing Suzlon Energy Ltd., exposing the foundations for its twenty wind energy generators (WTGs) at Behpur, Mandsaur, Madhya Pradesh, India. The foundations are circular footings set at shallow depths.
Sites for WTGs are selected based on where the intensity of wind is high over a major period of an average day. However, during intense rain or wind, soil erosion can be severe, and footings founded at shallow depths can get exposed. Geocells laid at the surface with appropriate infill protect against such erosion. The honeycomb structure of the geocells provides confinement to the infill and prevents it from being dislodged by the agents of erosion. The infill also nurtures vegetation within the cells, which not only offers added protection but also lends an aesthetic touch.
For this project, 3-inch (7.5-cm) deep geocells with 26-inch (66-cm) weld spacing were used.
The ground surface above the circular footings of each wind turbine was cleared of all rank vegetation and loose material. The soil was compacted to about 102 pounds/cubic foot (16 kN/m3) and a ground slope was maintained at roughly 1V:40H. Geocell panels were cut and placed to cover the circular profiles of the footings. Adjacent panels were connected together with high-strength cable ties. The geocells were infilled with local soil and compacted.
The geocells prevent erosion of the surface soil by confinement. Hence, hardly any maintenance or replenishment of soil cover is required. This reduces the life-cycle costs of the system.