Grouting mechanism of quick setting slurry in rock fissure with consideration of viscosity variation with space

Abstract

Quick setting slurry is commonly used in rock fissure grouting projects due to short gel time, high early strength and high retention rate in groundwater. Generally, quick setting slurry is composed by grout material and quick set reagent, and can be injected by using two-shot injection systems, which mixing two components inside or outside injection hole. Resulting from two-shot injection style and quick setting property of slurry, the viscosity of slurry varies from the injection hole to the radius of grout spread in grouting process, which has significant influence on the fissured rock grouting calculation. In this paper, grouting process of quick setting slurry in a single horizontal fissure is studied. The step-wise calculation method is proposed to describe the grouting process, considering the uneven distribution of slurry viscosity in grouted zone. The circular grouted zone is divided into infinitesimal annular elements, according to the moment when the slurry particle is injected into the fissure from the injection hole. Case studies of two conditions (constant grouting flow and constant grouting pressure) are investigated to capture the distribution of slurry viscosity and pressure in grouted zone. Fissure grouting test is performed to verify that the developed step-wise calculation method is suitable for the analysis of the distribution of pressure in grouted zone. Cement-sodium silicate slurry with two volume ratios (C:S=1:1, 2:1), a typical quick setting slurry, is used in the grouting test, and the pressure field and visual grouted zone are monitored in grouting process. The computed results derived from the step-wise calculation method is well consistent with the measured results, and the effectiveness of step-wise method is verified.