The assessment of innovative geotechnical slope repair techniques

Work to evaluate the effectiveness of innovative geotechnical slope repair techniques used on UK national highways is summarised. The techniques assessed were the planting of live willow poles, electrokinetic geosynthetics (EKG) and fibre-reinforced soil (FRS). These were used instead of conventional approaches to reduce the overall impacts of various challenges, including environmental constraints (habitat and visual) and access and utility constraints, and to reduce the scale and/or cost of traffic management and traffic delays. Trials have been undertaken over the last 20 years or so, but monitoring was generally limited to just a few years post-construction; longer term evaluation was not generally undertaken. The evaluated success – or otherwise – of the techniques led directly to recommendations for future use, ranging from the development of live willow pole design guidance and specification information, guidance on further EKG trials and cessation of the use of FRS, primarily on environmental grounds but also acknowledging the construction difficulties encountered. Life cycle analysis revealed that each technique provides significant carbon dioxide savings compared with rock fill replacement. More generic lessons learnt from the trials and the practical applications reported were used to produce guidance for future trials of innovative geotechnical repair techniques, including those for slopes.