Numerical Simulation of Chemical Grouting in Heterogeneous Porous Media

A mathematical model to simulate chemical grout injection, grout curtain formation in aiding rational design of chemical grout systems in saturated porous media is proposed. Three-dimensional modular groundwater flow simulation model (MODFLOW) and three-dimensional multi-species reactive transport (RT3D) model are combined and modules for the gelling process are incorporated to simulate the grouting process. The paper investigates the influence of varying degrees of soil heterogeneity and layering on grout barrier formation through numerically generated hydraulic conductivity fields. Layer persistence and range of conductivity can be specified during generation of conductivity fields. Grout barrier performance is assessed by simulation of grout injection in a three-dimensional domain followed by determination of post-grouted conductivity field and calculation of overall grout curtain hydraulic conductivity using a flow model. The simulation results show that spatial variability control the effectiveness of grout curtain performance. About 80–90% of the 25 hydraulic conductivity fields with high variability failed to reach the desired effective hydraulic conductivity.