Performance and Plugging Effect of Tunnel Leakage Plugging Materials

Water leakage in tunnels often occurs because of their significant buried depths and high water pressure, leading to economic losses and environmental damage. Therefore, research on the performance and plugging effect of plugging materials under high-pressure water conditions has become increasingly striking. In this study, early-strength sulfoaluminate cement, 5044N redispersion latex powder, and acrylate copolymer emulsion (ACE) were used as experimental materials to investigate the influence of polymer type and polymer-cement ratio on the ultraearly performance and plugging effect of tunnel leakage plugging materials. Our findings suggest that the initial and final setting times of plugging slurry produced with 5044N decreased by 14% and 19%, respectively, whereas the ACE delays the setting time of plugging slurry. 5044N can increase the viscosity mutation time of cement slurry by 40-120 s, and the mutation time and initial setting time are essentially the same. The variation in plugging slurry viscosity conforms to an exponential function. Similarly, the increasing trend of the viscosity of the plugged slurry also conforms to an exponential function. Based on the increase in the ultrasonic wave speed, the hydration process of the plugging slurry is divided into platform, mutation, and stable stages. A solid skeleton is formed during the mutation stage. The mutation time of the ultrasonic velocity is consistent with the final setting time. The mutation time of the slurry with 5044N increased by 248 s. During the mutation stage, the rate of solid phase formation increased by 55%-60%. The ultraearly performance of the plugging slurry with 5044N was the best at a polymer-cement ratio of 0.03. Scanning electron microscopy was used to analyze the composition of the clot at the mesoscopic level, and a large amount of C-S-H wrapped ettringite, filling the pores and increasing the density. In the leakage plugging experiment, the flow velocity in the leakage tunnel was used to quantify the plugging effect. The experimental results show that the plugging effect improves with increasing viscosity, and the plugging slurry with 5044N works in advance for 2 min. © 2022, Editorial Department of China Journal of Highway and Transport. All right reserved.