Investigation of the Expansion Effects on Grout Diffusion and Reinforcement in Fractured Rock Masses

Grouting is widely used to mitigate geotechnical hazards in underground engineering. However, conventional cement-based grouts often suffer from shrinkage-induced debonding at the grout–rock interface, thereby compromising reinforcement performance. Expansive grouts can effectively alleviate this problem; however, their expansion effects on grout diffusion and reinforcement have not been adequately investigated. This paper develops a numerical method for simulating expansive grout that incorporates both hydro-mechanical (HM) coupling effects and grout expansion effects. The proposed method is validated against laboratory tests. A three-dimensional numerical model of expansive grouting in a single-fracture rock mass is established to investigate the HM coupling and expansion effects on grout diffusion and rock deformation. The method is further applied to grouting reinforcement for a practical underground petroleum storage cavern project. Results indicate that the effective expansive agent contents above 3