# An Experimental Study on the Sealing Mechanism of a Karst Pipeline by Dynamic Water Grouting
## 1 Introduction  
China's engineering construction industry is undergoing rapid development. The country is building infrastructure such as hydropower and water conservation, tunnels, mining, highways, bridges, subways, and other projects in high demand. These underground projects frequently involve engineering sudden water, gushing water, seepage, and other water hazards, which, if not handled properly or in a timely manner, can easily result in poor construction quality, slow progress, financial losses, and other issues. Surge water has become one of the most common geology dangers in tunnel and subterranean construction [1; 2; 3; 4]. The most common and successful method of dealing with surge water disasters is grouting [5; 6]. Many scholars have conducted extensive research on the theory and technology of grouting in water-rich and weak peripheral rocks, fault fracture zones, and so on, yielding numerous valuable scientific research results [7; 8; 9]. However, karst, the most widely distributed and largest area in China, has not been adequately researched in terms of the theory and method of its grouting treatment. As one of the main types of water influx in karst areas, karst pipe-type influx is characterized by a high flow rate and high velocity, ss depicted in Figure 1. At present, there are few studies on the mechanism and method of water gushing in karst pipes at home and abroad, so it is of great significance and engineering application value to study the mechanism and method of water gushing in karst pipes. Traditional grouting materials have proven challenging to suit the needs of high-pressure, high-flow surge water projects, so developing new dynamic water grouting plugging materials has become a significant priority. Under dynamic water conditions, typical cement slurry is quickly diluted and scattered, and it cannot serve the job of a surge water sealer. Chemical slurry has been widely employed in gushing water control projects in recent years due to its benefits, which include resistance to dispersion under dynamic water circumstances, short setting time, high early strength, and superior profitability [10; 11; 12]. However, the general application of chemical grouting in the project may be limited by its potential for toxicity, environmental damage, high expense, etc. Thus, research into ways to increase grouting material retention rates, scour resistance, and ecologically friendly grouting material development in a dynamic water environment is crucial. At present, many scholars at home and abroad have conducted a lot of research on the aspect of grouting and sealing of fissured rock and soil, while achieving more results. [PERSON] et al. [13] developed an analytical model depicting the fissure grouting test in sand. [PERSON] et al. [14] carried out an experimental study on the closure effect of chemical grouting in rock fractures under dynamic water conditions. [PERSON] and [PERSON] [15] developed a grouting simulator based on the principle of parallel modeling to simulate grout flow in fractures. [PERSON] et al. [16] developed a full-size physical model for simulation studies of high-pressure fracture grouting in rocks deep underground. [PERSON] et al. [17] established an infiltration grouting model based on [PERSON]'s formula by taking the capillary force into account and proposed improved spherical and columnar grout diffusion formulas. [PERSON] et al. [18] investigated the theoretical model of slurry diffusion on the basis of the existing generalized Darcy's law and derived an infiltration diffusion radius formula for power-law type slurry in sandy soil formations. [PERSON] et al. [19; 20] established a single-fissure flat plate model and conducted orthogonal tests to clarify the sealing mechanism of grouted slurry under dynamic water conditions. [PERSON] et al. [21] proposed the applicable range of their grouting materials by studying the characteristic law of viscosity change with the time of quick-setting type grouting materials under dynamic water conditions.