Study on the Effect and Mechanism of MICP Technology for Repairing Static Load-Damaged Loess

To solve the engineering problem of loess mechanical degradation and reduced water stability due to static loading, this study applies MICP (Microbially Induced Calcite Precipitation) to repair statically damaged loess. Macroscopic effects were tested by unconfined compression, triaxial shear and slaking tests. The repair mechanism and key factors were analyzed via biological activity monitoring, SEM and XRD. Results show MICP significantly improves damaged loess properties: lightly to moderately damaged samples (2%~3% strain) have unconfined compressive strength 8.7%~15.7% higher than undisturbed loess, while severely damaged ones (5% strain) reach similar strength. The internal friction angle rises from 12.81° to 36° (restoring strength-confining pressure linear correlation), and slaking time is 5 times that of untreated loess. Calcium source concentration and curing time are core parameters; 2~2.5mol/L is optimal for Yanchi’s weakly alkaline loess (pH=9.1), generating 5~20μm cubic calcite crystals with best effect. Strength peaks at 14 days of curing, with residual mineralization potential at 28 days. Repair relies on the "biological metabolism-mineral cementation-mechanical enhancement" synergy, and MICP adapts well to loess’ weak alkalinity and low saturation, doubling slaking resistance under low concentration and short curing, supporting geotechnical repair in the Loess Plateau.