Triaxial compression test of MICP sand column and simulation of failure process

Microbial induced calcium carbonate mineralization (MICP) technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regulation of environmental factors, and it can be used as cementing agent to fill and cement cohesionless sand particles to form artificially prepared materials with the characteristics of strength, durability and environmental friendliness, which has a good engineering application prospect. In this paper, the compressive strength of sand column is tested by triaxial compression test, and the strength index is obtained. In order to further study the micro-strength mechanism and failure process of macro-strength, based on the Particle Flow Code(PFC) model of discrete element method, a numerical model of microbial-induced mineralization sand column was established considering the factors of matrix soil particle gradation, particle morphology, content ratio of induced calcium carbonate, pore distribution characteristics, inter-particle cementing and so on. The failure process of microbial induced mineralization sand column under load was numerically simulated, and the reliability of the numerical model was tested by combining with the stress intensity curve of samples under test conditions. The results indicate that, compared to the actual triaxial test of microbial-induced mineralization sand column, although there are deviations in stress and strain, cohesion and internal friction angle, the numerical simulation has the similar development law, the similar stress intensity amplitude, and the same failure trend. Therefore, the work done in this paper not only verifies the reliability of the numerical model, but also provides a theoretical basis for the subsequent analysis of the influencing factors of the geotechnical mechanical properties of biomineralized materials.