Effects of permeability, bacterial adsorption, and soil layering on entire MICP grouting process

Abstract The treatment of soils using the Microbially Induced Carbonate Precipitation (MICP) method involves intricate hydraulic, biological, and chemical processes. Due to constraints related to time, equipment, and cost, it is challenging to fully explore the grouting process solely through experimental methods. Therefore, in this work, we aim to elucidate the entire MICP grouting process using a multiphysics coupling model that captures fluid flow, transport of bacteria and chemicals, adsorption, desorption and straining of bacteria, reaction of chemicals, as well as variations in porosity and permeability. A two-phase strategy with controlled injection solution volumes was used, and our discussion primarily focused on the impacts of key soil properties, such as permeability, bacterial adsorption, and layering, on the MICP grouting process. The results highlighted the critical role of bacterial distribution in determining the final distribution of precipitates. Additionally, from an engineering application perspective, these factors affect both the efficiency of raw material utilization and the uniformity of soil stabilization. Specifically, permeability and layering primarily induced seepage-related waste, while the bacterial attachment coefficient contributed to conversion-related waste. This study provides a fundamental understanding of MICP grouting processes in both homogeneous and layered soils, which will be helpful for designing effective MICP grouting strategies in engineering applications.