Low Viscosity Polyurethane Modified Epoxy Resin Grouting for Steel Ring Reinforcement of Subway Tunnel

Steel ring reinforcement technology is an effective method to eliminate the damage of tunnel structure caused by ground load, surrounding foundation pit and underground water source. The grouting material used to fill the gap between the tunnel segment and the steel ring should have the characteristics of low viscosity, high strength, rapid curing at room temperature and anti-subway vibration. In this work, a special polyurethane modified epoxy resin grouting was fabricated to overcome the inherent brittleness of epoxy resin, and was combined with the reactive diluent and the amine curing agent to suit the above applications. The results showed that both tensile and impact strength of epoxy resin grouting modified by polyurethane were improved obviously compared with those without modification, presenting an obvious toughening effect. Although the viscosity increased slightly, it can still meet the perfusion requirements of steel ring reinforcement of subway tunnels.