Corrosion Level of Rock Bolts Exposed to Aggressive Environments in Nordic Road Tunnels

Abstract For road tunnels in most Nordic countries, temporary rock support installed during tunnel excavation usually becomes a part of the permanent support. Rock bolts are common measure excavated hard rock, and their conditions over period operation play significant role safety these tunnels. The bolt types aggressive environmental considered this research focused on those used observed Norwegian Swedish Findings elsewhere similar environments included to highlight different kinetics degradation. Based collected data, corrosion levels comparable polluted industrial areas. Aggressive groundwater for include pH below four (which can be caused by sulfuric acid formation due oxidation mineral pyrite rock), marine groundwater, flowing with high concentration dissolved oxygen. Furthermore, chloride-bearing deicing salts commonly roads located cold climate regions winter promote from room. environments, proposes lognormal probability function quantify expected steel level 25, 50, 100 years exposure time. protection given cement grouting, hot-dip galvanizing epoxy coating also addressed explore contributions lifespan extension acidic chloride-rich environments.