<p>Recently, foamed polymers have been widely used in the repair of underground engineering disasters by grouting (trenchless technology) due to controllable gelation time and self-expansion. However, the grouting process becomes more complicated due to the complex geological conditions and the self-expansion of slurry. Therefore, this paper adopts a self-made visual experimental device with peripheral pressure and water plugging rate (WPR) monitoring functions to study the influence of main influencing parameters (particle size distribution, grouting amount and dynamic water pump pressure (DWPP)) on the spatiotemporal distribution of slurry WPR and diffusion dynamic response (peripheral pressure). The results show that: When grouting amount is 563 g and DWPP is 0.013 MPa, the expansion force of the slurry in the diffusion process is dominant and can significantly change the local sand and gravel skeleton structure. When grouting amount is 563 g, DWPP is 0.013 MPa, and particle size distribution type is III, the flow time of the polymer is shortened, the pores of the gravel are rapidly blocked. Then, the peripheral pressure decreases rapidly with the increase of the distance, and the time to reach the inflection point WPR is shortened. The instantaneous blockage of the pores leads to the delayed transmission of flow field blockage information.</p>