Abstract: To systematically review the current application status of transparent soil technology in the study of grout diffusion within overburden layers and to explore its future development directions, papers related to grouting experiments and theories involving transparent soil cover layers were reviewed.Through a synthesis of research on transparent soil skeleton materials and pore fluid systems applicable to geotechnical engineering, the principles for determining similarity ratios in transparent soil grouting model tests for overburden layers were clarified.The optical fundamentals, information acquisition approaches, and recent advancements in digital image processing techniques for visualizing grout flow in transparent soil were summarized, highlighting the distinctive advantages of this technology in overburden grouting research.Building upon the application of transparent soil testing in theoretical investigations of grouting, the contributions of this technology were systematically reviewed in four major aspects: identification of key controlling factors in grouting, elucidation of grout diffusion mechanisms, optimization of grouting processes, and evaluation of reinforcement effectiveness.The results showed that: there were four critical issues in the application of transparent soil in current overburden grouting research: insufficient physical and mechanical similarity between transparent soil materials and natural overburden strata; inadequate similarity of grout materials and limiting the accurate representation of cement grout rheological behavior; pronounced scale and boundary effects as well as discrepancies between experimental interface conditions and actual engineering environments; predominance of qualitative analysis in existing studies with a lack of systematic quantitative investigations.The findings contribute to a deeper understanding of grouting mechanisms in overburden layers and reveal the complex interaction patterns between grout diffusion and overburden media.These insights can provide a reference for optimizing grouting engineering design and advancing theoretical and technological developments in grouting practice.It is proposed that future research should focus on: developing transparent overburden materials with mechanical properties highly consistent with natural strata; designing transparent grout systems with rheology characteristics comparable to engineering cement grout; establishing large-scale transparent soil experimental platforms to mitigate scale effects; and promoting coupled analyses integrating transparent soil experiments with numerical simulations, thereby facilitating the transition of transparent soil technology from a qualitative visualization tool to a quantitative predictive approach.The research results were conducive to in-depth exploration of the grouting mechanism of the covering layer and revealed the complex influence laws of grouting on the covering layer medium.The results can provide references for optimizing the design of grouting projects and promoting the advancement of grouting theory and technology.