Rehabilitation of Infrastructure After Road Slips on Steep Slopes

Abstract

Anastasios Mouratidis

Roads in the urban or rural environment may undergo severe deterioration due to flood events, erosion and drop of shear strength in the supporting infrastructure. Common features of this type of road deterioration are: [a] narrow head of slide [b] rotational or plane failure, [c] bottom-up distress due to soil erosion and degradation. In several cases, upgrading interventions can be very difficult because of limited access of mechanical equipment, necessary for rehabilitation operations. Especially, in case of road slides on steep natural slopes, rehabilitation of the soil infrastructure may encounter serious impediments: limited access to equipment, risk of total collapse in case of further excavation, hand transport of materials, limited width of the geostructure to be restored. Geotechnical engineers have to deal with all these constraints and conclude to the most suitable and the most realistic design of reconstruction for a safe road infrastructure. To this end, the geotechnical designer is driven to think “out of the box” and renounce the common supporting and buttressing techniques: retaining walls, pretensioned bolts, soil nailing. Instead, low-cost methods, alternative techniques and small-scale operations, may prove effective: staged excavation and reconstruction, nailed parapets, soldier-pile walls and other. These alternative techniques should be suitable for portable drilling equipment and hand-driven site works to rehabilitate the damaged road infrastructure and restore rideability on the roadway. In this paper, some of these alternative techniques are presented and related considerations on the geotechnical stability are outlined. Moreover, design sketches are displayed, aiming at guiding the geotechnical designer to small-scale rehabilitation solutions in case of flood- distressed road infrastructure on steep slopes.

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