Abstract
There are many drawbacks in traditional loess-strengthening technology. MICP (microbially induced calcium carbonate precipitation) technology provides a new approach to loess management, but there are few studies on loess solidification and a lack of engineering application research and verification. This study investigated the strength and microscopic mechanisms of loess solidified by the application of MICP technology combined with plant straw. The permeability conditions of loess for MICP technology were derived, and multiple sets of experiments were conducted using specific loess, Bacillus pasteurii, cementing solution, plant straw, and other materials. The experiments explored shear strength, unconfined compressive strength, microscopic properties, plant growth adaptability, and factors affecting bacterial growth. The results indicated that within the temperature range of 25-35 °C, the concentration and urease activity of Bacillus pasteurii were significantly affected by temperature, with the highest bacterial concentration observed at 30 °C. During scaled-up cultivation, increasing the inoculation ratio prevented a significant decrease in the urease activity of individual bacterial strains, and a 1% inoculation ratio was generally sufficient to meet the experimental requirements. When the loess density was 1.7 g/cm(3) and 1.8 g/cm(3), the cohesive force and internal friction angle in the experimental groups with added bacterial solution were increased by approximately 30% and 50% and 15% and 5%, respectively, indicating that MICP technology can significantly enhance the shear strength of loess.