A theoretical model for slurry infiltration in horizontally layered strata considering interlayer slurry transport

During slurry shield tunneling, slurry infiltration plays a critical role in excavation face stability. However, the infiltration behavior and interlayer transport mechanism of slurry in horizontally layered strata remain unclear. This study combines laboratory experiments with theoretical model development to investigate slurry infiltration in layered strata. Based on the modified Darcy’s law and mass conservation principles, a theoretical model incorporating pressure-driven interlayer slurry transport between adjacent strata is established and solved using an implicit finite difference method. The spatiotemporal evolution of excess pore water pressure, particle retention, and infiltration velocity is analyzed to reveal the infiltration characteristics and transport mechanism. The results show that slurry infiltration exhibits a staged evolution, with rapid growth at the early stage followed by gradual stabilization. Excess pore water pressure propagates from the excavation face into the strata, and the pressure difference between highly permeable and low permeability strata gradually decreases during infiltration. An obvious interlayer slurry transport phenomenon occurs, with slurry migrating from highly permeable strata to low permeability strata, thereby regulating the permeability contrast between adjacent strata. Parametric analysis indicates that slurry viscosity has a stronger influence on infiltration behavior than slurry excess pressure. Comparison between experimental results and model predictions demonstrates that the proposed model can effectively capture the early and intermediate stages of slurry infiltration in layered strata, providing a theoretical basis for slurry shield tunneling in complex geological conditions.