| Abstract:In shield tunneling, replacing the shield tail brushes with grouting method requires the formation of a closed and stable water stop ring, including a polyurethane ring and a slurry ring. . This paper combines the example of shield tunneling construction in a water rich sand strata by the sea,,and collects in-situ groundwater to conduct indoor test on the initial setting time, foaming rate, solid strength, etc. of polyurethane. The results show that hydrophilic polyurethane reacts rapidly with groundwater, forming a compact and uniform consolidated body, with low foaming rate and low strength, while the hydrophobic polyurethane is in the opposite state; On site actual injection can consider using both at the same time, first injecting hydrophilic polyurethane, then injecting hydrophobic polyurethane, and controlling the dosage according to 5:1.The on-site application has proven that the formed inclusions are stable and of good quality. |
