The Development of MICP Simulation Technique Based on Reaction Diffusion System

Abstract

The soil improvement technique called as microbially induced carbonate precipitation (MICP) is recognized to be more environmentally friendly than traditional techniques using piles or cement milk. The soil particles bind by precipitating calcium carbonate on particles or in pores, depending on microbial activity. Although the binding structures such as active and inactive bonds have been numerically simulated from chemical-based modelling, the simulation of carbonate precipitation taking into account microbial growth has not been carried out. In addition, the relationship between the spatial precipitation pattern and improvement of mechanical properties remains ambiguous. In this study, a novel MICP simulation scheme dealing with microbial growth is proposed, and the impact of carbonate precipitation on the mechanical properties of the MICP-treated materials is discussed. In this scheme, a reaction-diffusion system and a homogenization method are used for microscale bacterial growth and for multiscale stress and strain analysis, respectively. The results of the calcium carbonate precipitation were 4.5 μmol/mm3 at 10.3 hour, which is slightly higher than the experimental data. Furthermore, the homogenization simulations indicated that soil stabilization could be attributed to the formation of a novel skeleton structure comprising soil particles and calcium carbonate-filled soil pores.