Development of a Coupled BCHM-Model for Numerical Investigations of MICP treatment of Soil

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According to some recent research, microbially induced calcite precipitation (MICP) can obviously change soil properties in term of increase of mechanical stiffness and reduction of permeability. Therefore it provides a potential alternative environmental friendly solution to a wide range of engineering problems e. g. reinforcement of the soft underground, soil erosion control, seismic control, remediation for nuclides and heavy metal contamination. Since a large area in MICP especially the coupled bio-chemo-hydro-mechanical (BCHM) processes are unexplored, to date applying MICP to improve the soil properties can only be demonstrated in the experiment. Recently many experimental investigations have been conducted on MICP in soil. However as an essential tool for the analysis of the coupled BCHM issues in porous media the numerical framework for MICP is still at its early stage. Especially, research work with regard to the mechanical constitutive model on MICP and numerical model dealing with the mechanical related coupling effects is rare. Although the experimental analysis on the mechanical behaviour of the MICP treated soil have provided sufficient database for the development of the mechanical model for MICP treated sand.Considering the current research state of MICP the aim of this project is to investigate the mechanical constitutive behaviour of MICP treated sand and develop of a fully coupled BCHM model and herewith extend scientific basis for the MICP application. The specified objectives include: 1) to develop the mechanical constitutive model; 2) to extend our current BCH model to a fully coupled BCHM model 3) to develop a robust and computational efficient solution strategy for coupled problem 4) to calibrate and validate numerical model based on experimental data; 4) to analyse the sensitivity of model parameters.It is expected that through this proposed research the understanding of the coupled BCHM processes in MICP can be improved, the long-time and MICP behaviour in different scales can be reasonably predicted, the related future research area can be identified. Besides, the concept of coupled model and the solution strategy are expected to be adopted and applied in the modelling framework of further coupled issues in porous media.