Abstract
The use of microorganisms to induce desaturation of granular soils via denitrification results in nitrogen and carbon dioxide gas generation, which in turn lowers the degree of saturation of the soil matrix. Given sufficient substrates, the stimulated bacteria will produce enough gas to develop a continuous gas phase. Introducing gas into the soil to reduce the degree of saturation is shown to increase the soil resistance to dynamic loading and helps to mitigate liquefaction. The impact of desaturation on liquefaction hazard mitigation has comparative value to the calcite precipitation phase of the process. Meso-scale tests have been performed on a relatively thin tank of soil to simulate planar flow through a granular soil treated with MIDP.
Highlights
Microbial Induced Desaturation and Precipitation (MIDP) is an emerging bio-based ground improvement technique, which has potential for mitigating the potential for earthquake-induced soil liquefaction [1,2]
The objective of this study is to evaluate the effect of biogenic gas formation and migration on the volumetric water content and pore water pressure during MIDP treatment in granular soils in two-dimensional plane strain conditions using an instrumented meso-scale tank set-up
Meso-scale experiments were performed on a relatively thin tank of soil to simulate planar flow through a granular soil treated with MIDP
Summary
Microbial Induced Desaturation and Precipitation (MIDP) is an emerging bio-based ground improvement technique, which has potential for mitigating the potential for earthquake-induced soil liquefaction [1,2]. Similar to MICP by urea hydrolysis, precipitation of calcium carbonate minerals by MIDP may increase stiffness, strength and dilatancy or reduce permeability of granular soils by forming cemented wedges between the sand grains. Introducing gas into the soil to reduce the degree of saturation is shown to increase the soil resistance to dynamic loading and helps to mitigate liquefaction. The impact of desaturation on liquefaction hazard mitigation has comparative value to the calcite precipitation phase of the process. There are several methods to generate the partially saturated conditions such as gas injection [4], water electrolysis [5], and production of gas in situ through a chemical process [6]. Using biogenic gas through denitrification is another approach that has been reported to be feasible [7,8,9,10,11]
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