Tidal Effect on Grouting and Blocking of Flowing Water in Karst Fractures: Numerical Implementation and Its Application.

The issue of water blocking by grouting in coastal areas has engendered the need for a novel numerical simulation method for grouting with a flowing water under tidal action, two-fluid tracking (TFT). This paper proposes such a method. First, based on the material derivative, the transport model of the residence time of injected slurry was derived. In addition, the residence time of injected slurry microgroups at any grouting time was obtained by solving the transport model. Further, the numerical characterization of slurry viscosity during grouting in flowing water was realized by introducing a time-varying viscosity function obtained from previous experiments. Then, based on the generalized tidal action model, the diffusion behavior and blocking mechanism of slurry under tidal effects were studied. The results show that: (1) under tidal action, the water velocity fluctuates and decreases, whereas the grouting pressure fluctuates and increases; (2) at the early stage of grouting, the diffusion pattern of slurry appears as a droplet, and the tailing phenomenon becomes more serious with an increase of tidal intensity; with the progress of grouting, the diffusion pattern gradually changes to U-shaped or elliptical; (3) the strong tidal action will reduce the retention rate of slurry, which is not conducive to the grouting blocking. The research results have been applied to the grouting treatment of a China Resources Cement (Hepu) limestone mine. This research can provide some useful guidance for grouting treatment engineering of water inflow in coastal areas. [ABSTRACT FROM AUTHOR]