Design of reinforced soil structures using fine grained fill types

Large volumes of fine grained fill, which are not generally considered suitable for construction, are generated on construction sites. It is estimated that 500 million tonnes of construction and demolition (C&D) waste is generated annually in the European Union (EU), with over 11 million tonnes generated in Ireland in 2004. It was estimated that in 2001, 38% of the total C&D waste produced was excavated soil. Current design codes do not preclude the use of fine grained fill containing high proportions of fines (μ63 μm) in reinforced soil structures. This material can be successfully reused in reinforced soil structures, which can tolerate some deformation of the face and settlement at the crest. The deformation and settlement of the structure can be reduced by incorporating a drainage component in the body of the structure. The properties of four typical soils, which would not normally be considered as backfill material, are reviewed in terms of their classification, strength and consolidation characteristics. Design guidance on utilizing fine grained fills in traditional reinforced soil design processes is presented. Finally possible applications of this soil, using the modified design procedures, are identified.