Earth Retention and Soil Stabilization at Aamby Valley, Lonavala
|Principal Client||Sundesha Properties, Mumbai|
|Application||Earth Retaining Gravity Wall with StrataWeb®Geocells|
|Project Completion||May – June 2014|
The courtyard area in front of Sundesha Properties Bungalow at Aamby Valley was enduring heavy erosion since the monsoons of 2013. Scouring was critical at some places which caused collapse of soil wedges, causing slope stability failures at some locations. Aamby Valley is a hilly terrain and lies within the heavy rainfall zone of Lonavala. During the monsoon season, the problem was more critical, with possible slope failure which could undermine the plinths and endanger the foundations of the structure. A permanent engineering solution was sought, essentially to be implemented before the onset of the 2014 monsoons.
A retaining structure was proposed to contain the ground supporting the building foundations. The time period however was rather short to construct any conventional structure such as a masonry gravity wall or a reinforced concrete retaining wall. A gravity wall constructed of StrataWeb® Geocell Style SW356-300mm was proposed. The geocells are 300mm deep. The structure would stretch over 70m and would be 3m high.
The StrataWeb® gravity wall comprised of in-filled geocell panels placed one on top of the other. Initially, the bottom layers of panels were spread out with the help of steel spikes. Thereafter the panels were manually in-filled with local lateritic soil. The full depth of 300mm of the cells were filled and topped off with additional 25mm to 40mm of soil. A vibratory plate tamper was used to compact the in-filling. After trimming off the excess soil, the next row of panels was placed in position with the help of spikes. The panels were placed with an inward batter for better stability to line. Earth back fill behind the geocell panels was placed simultaneously to support the offset of the panels behind the wall due to the batter. The batter of each panel also created a ledge of soil to form a base to sustain vegetation.
Appropriate surcharge loads were also considered during the design of the system. The system was checked panel by panel for sliding and overturning. Individual cells are perforated and this allowed subsurface water that may have seeped into the slope to flow out without any build-up of pore water pressures. As a result, the wall was near vertical and yet maintained its integrity against sliding and overturning.
Benefits to Clients
- The StrataWeb® geocell gravity wall offer a rapid and aesthetic solution. The soil ledge created by the batter fosters vegetation.
- The solution is structurally sound and can withstand the fury of the monsoons of the Western Ghats.
- When compared with other systems, the StrataWeb® solution is more economical and the speed of construction is rapid. The key to this lies in the fact that local soil can be used for construction.
- StrataWeb® geocell gravity walls are excellent solutions for emergency construction during disasters, or when rapid construction is required without any specialised construction equipment.
- The solution is permanent, long-lasting and maintenance-free.