Influence of groundwater on splitting and fracture propagation mechanical properties of casing material

In sleeve-valve-pipe grouting, the casing material serves as a protective and flow-limiting layer, and its performance directly affects the quality and effectiveness of grouting. To investigate the influence of groundwater on the fracture initiation and propagation behavior of casing materials, this study employed a self-designed simulation device to conduct experiments on fracture propagation pressure, soil penetration characteristics, and material strength under different hydraulic head conditions (0 m, 2 m, 5 m, and 8 m). The results show that compared to dry conditions, the fracture initiation pressure of the casing material is significantly reduced under water-rich conditions. As groundwater pressure increases, the fracture propagation pressure rises from 155 kPa to 280 kPa, accompanied by an extended penetration distance and a more uniform distribution of grout in the soil. Groundwater pressure has little effect on the strength of the cured casing material slurry but significantly influences the fracture propagation pressure. These findings provide important guidance for parameter selection and process optimization in sleeve-valve-pipe grouting construction under water-rich conditions.