ANALYSIS OF SOLUTE TRANSPORT CONSIDERING VARIATION OF DRIVING FORCE FOR SOLUTION INFILTRATION IN POROUS MATERIALS

Abstract

 The solute transport behaviors in porous materials must be predicted to evaluate the performance of the sandy ground improvement and concrete structure repair by the injection of a chemical solution. This paper presents a simple analytical model for predicting the time variations in the solution concentration distribution by advection, mechanical dispersion and diffusion phenomena caused by the solution injection in porous materials. The governing equation for solute transport is derived by assuming that the solution infiltration by injection and solute diffusion in porous materials can be separately expressed as advection, mechanical dispersion and diffusion phenomena. Additionally, the advection term in the governing equation is defined by considering the effect of variation of the driving force for solution infiltration due to the pressure loss in pores of the porous materials. An analytical solution is derived by solving the governing equation, which is a nonlinear advection-diffusion equation. The analytical results suggested that the time variations in the solution concentration distribution depended on the advection phenomenon by the solution injection in the initial stage of the solute transport process, and that the solute was transported over a long period owing to the mechanical dispersion phenomenon.