Bio-mediated soil improvements phenomena have been observed though various experimental tests and investigations that the shear strength of microbial-mediated soils can be improved using the process of bio-chemical cementation. In the modern geotechnical community, this phenomenon is expected to become the focus of innovative technologies for use in next-generation soil improvement technologies. Also, the bio-chemical cementation is also observed in a natural environment. Thus, the microbially induced cementation in geo-materials is of interest from an engineering viewpoint because there is a possibility that this is applied artificially to natural environments. In contrast, predicting technique for microbially induced structural evolution of inner soil is still to be investigated in practice because we may not be able to change certain parameters easily with respect to the microbial activity. In this work, the authors attempt to bring a new perspective to the field of bio-mediated soil improvement technology, drawing on mathematical modelling and simulation techniques in order to understand the mechanism of microstructural formation and predict the future state of the soil. The mathematical model in microscale space is formulated by reaction-diffusion system where the metabolic reactions of microorganism are considered. Whereas, the mechanical behavior in macroscale space is calculated by a homogenization technique.

1. Introduction

Over the last century, various numerical and experimental methodologies for soil improvement have been investigated (DeJong, et al., 2006). In these investigations the soil improvement technologies have been developed experimentally and empirically from several viewpoints such as geotechnical engineering, geomechanics, chemodynamics, and microbiology (Alvarez and Steinbach, 2009). In particular, the microbiological viewpoint has attracted attention, and microorganisms have been used in soil improvement technique (Whiffin, et al., 2007). This approach has been considered to be friendly more than traditional engineering technique in natural environments because some microorganisms in a natural environment can be used for soil improvement (DeJong, et al., 2006).

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