Two-phase analytical model of seepage during grout consolidation around shield tunnel considering the temporal variation in viscosity and the infiltration effect

Abstract

Studies on grout consolidation after synchronous grouting around shield tunnels have ignored the expansion of the grout–groundwater interface and the difference in the permeabilities of the grout and water in the stratum. The process of grout pressure dissipation and diffusion in the stratum was solved with a two-dimensional two-phase seepage model, with which the head losses caused by grout diffusion in the stratum and groundwater seepage in the stratum under the ‘push-displacement effect’ were studied together. In addition, the influence of the temporal variation in viscosity and the infiltration effect were considered. Then, a two-phase analytical seepage model of consolidation for shield grouting considering the temporal variation in viscosity and the infiltration effect was established. A numerical algorithm was designed to solve the theoretical model with the difference method. The analytical model was verified by comparison with the results of numerical simulation. Furthermore, the main parameters in the analytical model were analysed. The results show that the temporal variation in grout viscosity and the infiltration effect greatly influence the stable pressure value and the loss rate of the volume of grout after consolidation. Among the main parameters in the model, the permeability coefficient of the stratum is the most sensitive.