GFRP anchoring systems for soft-rock geostructures with high cultural and environmental value

Structural instability of soft rock geostructures composed of carbonate rocks (such as chalk and calcarenites) and volcanic (tuff) is a serious problem especially when it develops in inhabited centers. Because of the carbonate rich geology, geohazards such as sinkhole and cliff instability are a real threat for inland and coastlines regions of both southern Italy and other regions across the world. The areas affected by such threat often coincide with cultural heritage sites because of their evocative landscape and they represent important nation landmarks, as the white cliffs of Dover in the UK. One of the problems related to the safety of these famous landmarks is the identification appropriate intervention measures able to preserve the originality and beauty of the site. For example, the use of standard shotcrete or rock anchors would result inappropriate as the steel plates of the anchors and the reinforced portions covered by shotcrete would alter the exposed surface significantly. In this paper a novel anchoring system aimed to overcome the above limitations is proposed and its performance is demonstrated by an intensive field testing campaign. By using Glass Fiber Reinforced Polymers (GFRP) bars combined with various types of consolidants, it is shown that that the same level of reinforcement, guaranteed by using standard grouted DYWIDAG steel bars, can be achieved with a setup characterized with lighter, more transparent and corrosion resistant materials.