The fronts of two rock glaciers located in South Tyrol (Italian Alps) failed on 13 August 2014, initiating debris flows in their downslope channels. A multimethod approach including climate, meteorological, and ground temperature data analysis, aerial image correlation, as well as geotechnical testing and modeling, led to the reconstruction of the two events. An integrated investigation of static predisposing factors, slowly changing preparatory factors, and potential triggering events shed light on the most likely reasons for such failures. Our results suggest that the occurrence of front destabilization at the two rock glaciers can only partly be explained by the occurrence of heavy rainfall events. Indeed, antecedent hydrological and thermal ground conditions were characterized by a saturated active layer favored by a snow‐rich winter and extensive precipitation in late spring and summer. Also, the rising trend of air temperature during spring and summer months since 1950s might explain the concurrent marked displacement of the two rock glaciers. Indeed, geotechnical investigations have provided strong indications that one of the investigated rock glacier fronts was at a marginally stable state prior to 2014. As rainfall events more intense than the one that occurred in August 2014 were previously recorded in the same area without resulting failures at the studied rock glaciers, we propose that both predisposing and preparatory destabilizing factors have played a key role in the 2014 rock glacier front failures.

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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.

The effective design, specification and construction of Special Geotechnical Measures (SGMs) is critical to the efficient operation of the National Highways Strategic Road Network (SRN). Given the required performance of the SRN in terms of resilience, reliability, redundancy and recovery it is essential that SGMs are themselves reliable in terms of performance and life; resilient to external conditions such as earthworks deterioration and extraordinary conditions (e.g. climate change). Around 100 different types of SGMs are used on the SRN and the early installations of some SGMs are approaching the end of their design life and the design, specification and application of many of these techniques is based on limited studies. This Information Note on Soil Nails is part of a series that reports on investigations of specific SGMs and makes recommendations on their future use