Liu Rentai

Theoretical and experimental research on the grout fronts diffusion considering filtration effect

Based on the seepage continuity equation, Darcy law, mass conservation equation, linear filtering law and pressure drop equation, the theoretical model of grout fronts diffusion was established. And through the model, the filtration mechanism of cement particles and the diffusion law of slurry fronts were analyzed. By applying the model test system developed independent, the dynamic variation law of the pressure of grout fronts is studied and compared with the theoretical value. The results show that, the permeability coefficient of the precipitated cement increases along the grout diffusion distance under the filtration effect. The change rate of frontal velocity is negatively correlated with the permeability coefficient of precipitated cement. At the specific diffusion distance, the frontal pressure drop p increases first and then decreases, while the frontal pressure p and the average unit pressure drop Δ P show the trend of decreasing first and then increasing. The deviation rate of frontal pressure value between theory and test is only from –10% to 26%, which reveal a high degree of coincidence. The conclusions can be used to guide the grouting design, which has certain application value to the practical engineering.