Two large-scale injection experiments, and assessment of the advection–dispersion–filtration model Available to Purchase

An assessment is presented of the validity of a theoretical model for miscible grout injection in a deformable porous medium. The mathematical formulation couples analysis of the fluid flow and the grout mass transport with a study of the solid skeleton's displacements and the porous medium stucture evolution. In particular, hydromechanical coupling, grout dispersion and filtration were considered in order to produce a realistic model of injection within a saturated deformable soil. The results of the theoretical formulation were compared with those obtained from two original large-scale injection tests performed in the laboratory. Controlled laboratory tests permitted study of the basic characteristics of fluid flow and grout propagation for a micro-cement grout, and an examination of the performance of the complete injection model was made possible. A numerical solution of the formulation was performed using the finite element method, and good agreement was obtained between the experimental and numerical results. The measured pore fluid pressures, soil displacements, grout front positions, porosities and hardened bulb dimensions were compared with their numerical counterparts. While the first large-scale injection experiment confirmed the fundamental assumptions made during writing of the model, the second injection test offered a complete phenomenological validation procedure, thus illustrating the capacity of the model to reproduce the behaviour of the porous medium during the injection, for a situation similar to a real injection operation.