Walls and Slopes

Project description

During the summer of 2007 the UK was hit by a number of severe storms which caused major disruption to the infrastructure network. Unusually heavy rainfalls weakened the embankment of the A6102, which is a major commuter route to the centre of Sheffield, leading to its failure and collapse into the River Don. The highway supported by the embankment was deemed unsafe and closed to traffic whilst a suitable solution was sought.

Solution

Due to the unstable condition of the slope and associated slip debris, determination of the exact nature and extent of the reinstatement works was not feasible, hence an adaptable solution was required. It was decided by the client’s designers White Young Green, to stabilise the embankment toe with concrete piles and reconstruct the main embankment with a steep reinforced soil slope. The reinstated slope had an inclination of up to 60° and a maximum height of 10m over a length of approximately 60 m. The upper part of the embankment was unreinforced with a slope inclination of approximately 27°.  The reinforced soil embankment comprised a wraparound face construction, which used various strength grades of geogrids, with a front face consisting of top soil and a green mesh incorporated behind the geogrids. Upon completion, the reinforced soil embankment was hydro-seeded with a drought-tolerant seed mix to aid and promote vegetation and help the reconstructed slope blend into the scenic Don Valley.  The geogrid polymeric soil reinforcement provides a cost effective alternative to more ‘conventional’ retaining solutions. The geogrid’s high-modulus, low-creep characteristics ensure slope deformations are minimised, ensuring long-term performance.

Benefits

• Very flexible solution in construction, engineering and landscaping
• Excellent integration with the existing environment
• The geogrid allows the re-use of local fill
• Economical solution
• Environmental solution - lower CO₂ emissions compared to alternative construction solutions