Grouting Model Experiment of Karst Aquifer under Dynamic Water Pressure and Confining Pressure

Abstract

Grouting plays an important role in the construction of projects. The influence of dynamic water pressure and confining pressure on grouting has not been considered by traditional grouting theory. This study used a "geological engineering multifunctional experimental system" to explore the influence mechanism of dynamic water pressure and confining pressure on the grouting effect. Four groups of indoor grouting model experiments were adopted and compared. The influence of dynamic water pressure and confining pressure on the grouting effect was analyzed under different conditions. Experimental results demonstrate that the diffusion of the slurry is divided into pressure diffusion and migration diffusion. The dynamic water pressure causes the grouting slurry to be diluted, and the pressure in the cracks of the rock mass structure increases. As a result, serious loss of slurry occurs, and the slurry obviously shows migration diffusion. The confining pressure leads to closing of structural cracks, and the grouting effect of closed cracks mainly affect the pressure diffusion of the slurry. A coupling effect exists between the dynamic water pressure and the grouting pressure. The final dynamic water pressure increases by 25% compared with the initial value under dynamic water pressure only. By contrast, the final dynamic water pressure increases by 31% compared with the initial value under the combined effect of dynamic water pressure and confining pressure. The grouting effect can be improved by increasing the grouting pressure, decreasing the dynamic water pressure, and extending the grouting time.