A Revised Porous Media Model of Microbially Induced Carbonate Precipitation for Loess Solidification

Abstract

Similar to sand solidification with microbially induced carbonate precipitation (MICP), the MICP technique can also be used to bond loess particles and improve the collapsibility of loess. However, existing theoretical models related to MICP sand solidification cannot be used to guide the application of loess solidification. Based on the properties of loess, the present study revised the transport model of biomass. The revised biomass transport model enabled the calculation of the biomass distribution. Moreover, considering the effects of nutrients in the cementation solution and the ions of inorganic salts contained in loess on urea hydrolysis, a new urea hydrolysis equation for MICP loess solidification was obtained. A revised theoretical model for loess solidification is proposed. In addition to the biomass distribution, the contents and distribution of calcium carbonate, and the porosity of solidified loess were calculated using the proposed model. The results are consistent with the results measured during loess solidification tests, demonstrating the feasibility and practicability of the proposed model. This revised theoretical model lays a solid foundation for the solidification of loess and preventing loess from collapsing.