Sustainable and environmentally friendly reinforced soil slopes and walls constructed with draining geogrids: Recent UK experience

Research has shown that geotechnical engineers and the construction industry in general like to think of themselves as working to benefit the environment and providing for future generations in tandem, if not always in harmony, with nature. However, engineers still prefer to work with high quality and expensive imported granular fill, rather than seriously consider using recycled spoil generated as part of construction activities. Engineers can design reinforced soil structures using marginal poorly drained fills without the need to import granular fill, which has both cost and environmental implications. Marginal fills typically have high silt and/or clay contents which, when loaded, have the potential to generate excess pore water pressures in the structural backfill. Poor drainage in the structural fill reduces the available strength of the fill, thus reducing the bond between the fill and the geogrid reinforcement. Therefore, to use marginal fill efficiently, adequate drainage must be provided in the reinforced soil structure. By using a novel geocomposite that combines reinforcement and drainage into a geogrid sustainable and environmentally friendly slopes and walls can be designed and constructed. Between 2015 and 2017 an innovative design methodology and approach for the construction of reinforced slopes and walls, up to 17m in height, with low-permeability fills was successfully used in the UK. The design and construction experience gained in the UK is presented to confirm the effectiveness of the system and given engineers confidence in the use of marginal fills in reinforced soil systems.