Model tests on curtain grouting in water-rich broken rock mass

The multiple drillings and sequenced curtain grouting experiment for water-rich broken rock mass is carried out using self-developed 3D grouting model test system. The spatio-temporal characteristics of total pressure, pore pressure and displacement are obtained by the optical fiber parallel real-time monitoring system. The total pressure and pore pressure greatly change and have 4 periods: rapid growth, peak-value fluctuation, progressive attenuation and gradual stability. The slurry advantage-fracture diffuses in the vault and arch bottom, leading to displacements around the tunnel. The permeability decreases because of compression and consolidation of the grouted rock mass, and the pore pressure is significantly improved during sequent grouting. After the grouting experiment, the reinforced body is exposed and its irregular form is studied. The penetration-splitting grouting reinforcement model for broken rock mass and the splitting grouting reinforcement model for argillaceous weak rock mass are summarized. The mechanism of repeated grouting of splitting grouting veins is revealed. The SEM images of grouting-reinforced body reflect that the interface between grouting vein and clay can be divided into penetrating type and split type, and the micro slurry veins improve the surface roughness and strength. A fractured crack develops to be closer to the clay, which suggests that physical and mechanical saltation takes place over there, which is the potential broken link of reinforced rock mass. The research improves the grouting experiment method and explores the slurry diffusion laws and grouting reinforcement mechanism, thus providing technical support for grouting management under similar conditions.