The Assessment of Innovative Geotechnical Slope Repair Techniques

This paper summarises work to evaluate the effectiveness of innovative geotechnical slope repair techniques used on National Highways’ slopes. The techniques assessed were live willow poles, Electrokinetic Geosynthetics (EKG) and Fibre Reinforced Soil (FRS) used in place of conventional approaches to reduce the overall impact of various challenges including environmental constraints (habitat and visual), access and utility constraints, and to reduce the scale and/or cost of traffic management and traffic delays. Trials were 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 willow pole design guidance and specification information, guidance on further EKG trials, and the cessation of use of FRS, primarily on environmental grounds but also acknowledging the construction difficulties encountered. A life cycle analysis shows significant carbon saving compared to rock fill replacement for each of the techniques. More generic lessons learnt from the trials and the practical application reported were used to produce guidance for future trials of innovative geotechnical repair techniques, including those for slopes.