Coupled multiphysical model for investigation of influence factors in the application of microbially induced calcite precipitation

The study presents a comprehensive coupled thermo-bio-chemo-hydraulic (T-BCH) modeling framework for stabilizing soils using microbially induced calcite precipitation (MICP). The numerical model considers relevant multiphysics involved in MICP, such as bacterial ureolytic activities, biochemical reactions, multiphase and multicomponent transport, and alteration of the porosity and permeability. The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields. It was implemented in the open-source finite element code OpenGeoSys (OGS), and a semi-staggered solution strategy was designed to solve the couplings, allowing for flexible model settings. Therefore, the developed model can be easily adapted to simulate MICP applications in different scenarios. The numerical model was employed to analyze the effect of various factors, including temperature, injection strategies, and application scales. Besides, a T-BCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate. To understand the scale dependency of MICP treatment, a large-scale heterogeneous domain was subjected to variable biochemical injection strategies. The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation. Additionally, the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment. The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-, prototype-, and field-scale scenarios.