Estimating Diffusion Radius Grouting into Broken Rock Mass

The influencing factors of grouting diffusion in broken rock mass were divided into four classifications: grouting pressure, grouting time, permeability coefficient and grout viscosity. Relations among similar factors were expressed to each other using an equation. Empirical formulas of relations among grout water-cement ratio, viscosity and time between the joint density of broken rock mass and permeability coefficient, and between water absorption and permeability coefficient were established. The differences among the four diffusion radius formulas grouting in porous continuous media were compared. A new empirical formula of diffusion radius was obtained using multivariate nonlinear fitting analysis based on the mean value of the four empirical formulas. The tests of grouting diffusion in broken rock mass were done in the field. The mean empirical formula is consistent with the measured value of the field tests on grouting diffusion radius, which provide a reference for the design of grouting into broken rock mass.