Geophysical methods for monitoring soil stabilization processes

Area of Science:

• Geotechnical Engineering
• Environmental Science
• Microbiology

Background:

• Soil stabilization is crucial for supporting engineered structures and managing subsurface environments.
• Microbial induced carbonate precipitation (MICP) is an environmentally friendly method for soil strengthening.
• Calcite precipitation, often microbe-mediated, offers a sustainable approach to altering soil properties.

Purpose of the Study:

• To investigate the efficacy of spectral induced polarization (SIP) and shear-wave velocity (SWV) in monitoring MICP-driven soil strengthening.
• To assess the potential of these geophysical methods for characterizing and long-term monitoring of soil stabilization projects.
• To validate geophysical findings with direct soil analysis methods.

Main Methods:

• Inducing carbonate precipitation in soil using microbial processes (MICP).
• Applying spectral induced polarization (SIP) to measure electrical properties of the soil.
• Measuring shear-wave velocity (SWV) to assess changes in soil stiffness.
• Confirming calcite precipitation using direct sampling and Scanning Electron Microscopy (SEM).

Main Results:

• Both SIP and SWV demonstrated sensitivity to calcite precipitation during MICP.
• SIP provided additional insights into the long-term stability of the precipitated carbonate.
• Geophysical monitoring results were consistent with direct methods (SEM, sampling), confirming soil strengthening and permeability alteration.

Conclusions:

• Geophysical methods, specifically SIP and SWV, are viable tools for characterizing and monitoring MICP-based soil stabilization.
• These methods offer a non-destructive and effective way to assess soil strengthening and permeability changes.
• This study supports the integration of geophysical techniques into MICP applications for improved project viability and environmental management.