An innovative “geo-carpet” system as a countermeasure against local scour at bridge piers: small-scale test results

Local scour around bridge piers is one of the most diffused causes of failure for river bridges since it considerably modifies the geometry of the riverbed around the foundation. Countermeasures have been proposed in terms of both bed armoring and flowaltering devices. In this field, the use of Geosynthetics can provide innovative solutions, with environmental, economic and technological benefits compared to more traditional approaches. In the paper some flume experiments, run in clear-water flow conditions on a circular pier in a homogeneous granular riverbed, are described. The tests included four runs where the area around the pier was covered with innovative “Geo-carpet” systems made by plastic nets with different mesh size, and one reference test on an unprotected pier. The results, at least for a single hydro-dynamic condition, showed the efficiency of the Geo-carpets on the reduction of the scour depth and volume, and pave the way to future experiments investigating different geometries and flow conditions (including live-bed scour).