Abstract:Wave-induced erosion poses a significant threat to the integrity of coral reef shorelines, resulting in the destruction of the foundations of marine structures and emerging as a key factor affecting the structural lifespan of ports, lighthouses, and other coastal infrastructure. The application of grouting technology to reinforce fractured reef limestone strata holds significant engineering importance, as it enhances the durability and stability of the foundations of these marine structures. Within these strata, the mixture of coral sand and reef limestone fragments is a prevalent geological structure. The study of the diffusion patterns of cement grout within this mixture is crucial for the grouting reinforcement and construction design of fractured reef limestone strata. This research utilizes indoor permeation grouting tests combined with numerical simulations to explore the influence of cement grout characteristics and mixture properties on grout diffusion. The study compares the diffusion behavior of three types of cement grouts with different solid particle sizes in mixtures of coral sand and reef limestone fragments with varying proportions, establishing the favorable permeability range for cement grout diffusion in typical reef limestone fractured zones and revealing the interactive effects of solid particle size and grout viscosity on grout diffusion distance. Additionally, the study analyzes the influence of filtration effects on grout diffusion distance from the perspectives of permeation channels and grout diffusion velocity. The results indicate that the characteristic parameters influencing grout diffusion distance are ranked in order of importance as follows: water-cement ratio, mixture permeability coefficient, grouting pressure, and cement particle size d90. The permeability performance of different grouting media determines the ranking of the three typical cement grout grouting capacities. In practical grouting projects, a balanced consideration of solid particle size and grout viscosity based on the permeability properties of the fractured reef limestone strata is essential for selecting the grout with optimal diffusion distance.