Assessment of Innovative Slope Repair Techniques

Abstract

This paper summarises work to evaluate the effectiveness of innovative geotechnical repair techniques for Highways England’s slopes. The techniques assessed were live willow poles, fibre reinforced soil (FRS) and electrokinetic geosynthetics (EKG) used in place of conventional approaches in order to reduce the overall impact of various challenges including environmental constraints (habitat and visual), access and utility constraints, and the need to reduce the scale and/or cost of traffic management and traffic delays. Trials of these techniques 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 has not generally been undertaken. This paper presents a summary of the assessment of the effectiveness of live willow poles, FRS and EKG as aids to increased stability. The success, or otherwise, of the techniques led directly to recommendations for future use ranging from the development of design guidance and specification information for willow poles, guidance on the execution of further trials of EKG, to the cessation of use of FRS. The results of a life cycle assessment (LCA) are reported, and 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.