Creep damage characteristics of microbially induced calcite precipitation-treated fractured sandstone: Experimental and particle flow approaches

The microfractures in a rock are critical factors inducing creep-related disasters, while the microbially induced calcite precipitation (MICP) technology has demonstrated remarkable efficacy in repairing such microdefects. Hence, in this study, to analyze the improvement effect brought about by the MICP technology on the creep damage of fractured rocks, experimental methods were employed to investigate the macroscopic creep characteristics and microbial mineralization features of repaired rocks. Based on the fundamental principles of particle flow and microscopic experiments, a numerical model integrating clumps with random geometry (CRG) and MICP (CRG-MICP) was developed to simulate the creep characteristics of the repaired rocks. A damage equation for the creep process of repaired sandstone was derived using the first law of thermodynamics and the CRG-MICP model. The results showed that the circularity and size of the microbial mineralization crystals initially increased and then decreased with the CaCl 2 concentration. During the creep process, elastic energy primarily accumulated in the elastic loading stage and was gradually but entirely released during the steady-state creep phase due to crack propagation and mineral friction. The rock damage parameters and CaCl 2 concentration exhibited evident Gaussian distribution characteristics, and the creep damage control effect was most pronounced in the CaCl 2 concentration range of 1.25−1.75 mol/L. The study findings hold significance in revealing the cross-scale mechanisms by which biomineralization regulates the mechanical response of rocks. • Collodion concentration significantly influences MICP mineral particle growth. • A CRG-MICP model simulates creep damage in microbially repaired fractured sandstone. • Energy evolution analysis reveals elastic energy storage and dissipation trends. • Microbial repair improves creep resistance, reducing damage parameters significantly. • Optimal CaCl 2 concentration (1.25–1.75 mol/L) enhances rock creep damage control.