A numerical model for two–phase immiscible fluid flow in a porous medium

Abstract

Chemical grouting may be defined as the injection of chemical mixtures, known as grouts, into the pore space of the soil. It is extensively used for ground stabilization in the construction industry. The mechanism by which injected grout permeates a soil mass involves a complex interaction of both chemical and physical factors that are not well understood. The objective of this work is to develop a two–dimensional numerical model for the computation of a two–phase immiscible flow in a porous medium. The phases of flow are grout and water. It is assumed that the phase of grout is non–wetting type. An important aspect of the chemical grout—hardening of the grout mix—is considered in the model. The coefficient of hardening is a parameter that represents the gelation behaviour of the chemical grout mix. The numerical model applied is based on a finite difference scheme known as vector volumes. The model is capable of estimating the order of magnitude and distribution of pore pressures that are developed during the injection process and the effects of non–homogeneities such as variations in permeability. The results are checked against laboratory tests. In practice, the numerical model may be used to avoid the expensive and time–consuming laboratory tests.