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

Abstract

Microbially induced calcium carbonate precipitation (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 MICP can be used as a cementing agent to cement cohesionless sand particles to form the materials with the characteristics of higher strength, better durability and environmental friendliness, as well as a good engineering application prospect. In this paper, the shear strength of sand column was tested by triaxial compression tests, and the strength index was obtained. In order to further study the micro-strength mechanism and the failure process, based on the discrete element method, a numerical model of MICP cemented 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 cementation and so on. The failure process of MICP cemented sand column under load was analysed by numerical simulation, 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 with the actual triaxial tests of MICP cemented sand column, although there are deviations in stress and strain, cohesion and internal friction angle, the numerical simulation shows similar development law and intensity amplitude, and the same failure trend. The work in this paper verifies the reliability of the numerical model and provides a theoretical basis for the subsequent analysis of the factors influencing the geotechnical mechanical properties of biomineralized materials.