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Geophysical Methods for Monitoring Soil Stabilization Processes
Citation:
Saneiyan, S., D. Ntarlagiannis, D Werkema, AND A. Ustra. Geophysical Methods for Monitoring Soil Stabilization Processes. JOURNAL OF APPLIED GEOPHYSICS. Elsevier Science Ltd, New York, NY, 148:234-244, (2018).
Impact/Purpose:
Highlights • Soil stabilization processes increase soil stiffness and are typically long term projects. • Soil stabilization processes require continuous, high resolution monitoring. • Geophysical methods offer high temporal and spatial capability, cost efficiency, and noninvasiveness. • Geophysical methods could be suitable for long-term monitoring applications. • Shear-wave velocity is a geophysical method. It is commonly used by engineers in ground improvement projects. • Spectral induced polarization (SIP) is a geophysical method with environmental applications. • SIP is shown to be sensitive to microbial cells, biofilm formation and biogeochemical processes.
Description:
Soil stabilization involves methods used to turn unconsolidated and unstable soil into a stiffer, consolidated medium that could support engineered structures, alter permeability, change subsurface flow, or immobilize contamination through mineral precipitation. Among the variety of available methods carbonate precipitation is a very promising one, especially when it is being induced through common soil borne microbes (MICP – microbial induced carbonate precipitation). Such microbial mediated precipitation has the added benefit of not harming the environment as other methods can be environmentally detrimental. Carbonate precipitation, typically in the form of calcite, is a naturally occurring process that can be manipulated to deliver the expected soil strengthening results or permeability changes. This study investigates the ability of spectral induced polarization and shear-wave velocity for monitoring calcite driven soil strengthening processes. The results support the use of these geophysical methods as soil strengthening characterization and long term monitoring tools, which is a requirement for viable soil stabilization projects. Both tested methods are sensitive to calcite precipitation, with SIP offering additional information related to long term stability of precipitated carbonate. Carbonate precipitation has been confirmed with direct methods, such as direct sampling and scanning electron microscopy (SEM). This study advances our understanding of soil strengthening processes and permeability alterations, and is a crucial step for the use of geophysical methods as monitoring tools in microbial induced soil alterations through carbonate precipitation.
