Numerical investigation of the gel barrier formation with vertical injection pipe

Permeation grouting is the injection of a fluid grout into ground and production of a solidified mass to carry increased load and/or fill voids to control water flow. This study examined a technology of constructing horizontal gel barrier by the permeation grouting through multiple vertical injection pipes. Colloidal Silica (CS) solution was used as a gelling liquid to be injected and solidified in the unsaturated soil. Formation of a gel bulb was simulated and the results were compared with those obtained from the sleeve pipe injection with horizontal pipes. The gel bulb generated from the injection method employing vertical pipe showed greater sensitivity of the bulb’s lateral extent to variations in operating conditions compared to the sleeve pipe injection. Although in the limited numbers, in all examined cases, the vertical-pipe system appeared to consume a larger volume of CS solution than the horizontal-pipe system to form an equivalent horizontal gel barrier. This result supports our intuition that the injection with the horizontal pipes may be more effective than the one with vertical pipes in constructing horizontal gel barrier.