3D Discrete Element Modeling of Sands Treated by Microbially Induced Calcium Carbonate Precipitation

Microbially induced calcium carbonate precipitation (MICP) has the capability to improve engineering properties of sands and has attracted plenty of attentions recently. 3D discrete element modeling is conducted herein to investigate the MICP process from the perspective of micromechanics. The sand particles are represented by large particles and the calcium carbonate (CaCO3) formed during the MICP process are modeled with fine particles. The sand skeleton is formed first with coarse particles only, and random fine particles are generated within the pore space of the skeleton thereafter. The fines precipitate to the interparticle contacts or particle surfaces under random external driving forces, which is designed to mimic the MICP process in reality. Different roles of fines, including pore-filling, coating and bonding, are formed naturally during the virtual precipitation process given the randomness. The good agreement between the numerical results and the experimental data validates the proposed model and proves its capability and potential for modeling the mechanical responses of MICP-treated sands and analyzing the underlying mechanisms.