Polyurethane resin (PUR) has been used for many years in the mining industry, but only recently has the technology gained a foothold in the geohazard mitigation industry. PUR can be used by itself to solidify rock masses, or can be used in combination with rock bolts or dowels to reduce the total number of anchors needed (and total project cost). Because PUR is “invisible” after installation, it is excellent option for aestetically critical sites where rock anchors, mesh, or shotcrete would not be acceptable.
Based on successes in Colorado and other Western States, the Tennessee Department of transportation selected multiple demonstration sites across the state to examine the installation requirements and application of a high-strength, two-component polyurethane resin to effectively “glue” unstable rock masses in place. GSI® engineers, working with experts from the resin manufacturer, designed the layout of the drill holes. GSI® Rockfall Remediation Technicians then drilled holes in the rock up to 20 feet deep. The resin was carefully injected in stages using packers. GSI® engineers were on site during these installations to verify migration of the PUR based on material take and where the PUR exited the rock face during the staged injection.
After multiple freeze/thaw cycles, all sites are completely in-tact with no further rockfall issues.
A variation of karst sinkhole grouting is the grouting of mined coal seams and workings located below existing infrastructure that exhibit the potential to propagate to the surface and cause sinkholes and/or subsidence.