Application of Microbially Induced CaCO₃ on the Reinforcement of Rock Discontinuity

Microbially induced calcium carbonate precipitation (MICP) is a technique used in geotechnical engineering to reinforce soil and rock. While it is commonly used for soil reinforcement, its application for rock reinforcement in saline–alkaline environments is limited. In order to improve the reinforcement effect of microbially induced calcium carbonate on rock joints in saline–alkaline environments, experiments were conducted to cultivate Sporosarcina pasteurii. The strengthening effects of MICP on rock joints were evaluated using the direct shear test. Samples of sandstone with rough surfaces were reinforced by MICP. The shear strength characteristics of rock joints reinforced by CaCO₃ were then assessed. The results showed that after being domesticated in a saline–alkaline environment, the bacterial concentration reached over 96% of that in a neutral environment. The domesticated Sporosarcina pasteurii performed well at temperatures between 10~30 °C in saline–alkaline conditions. In the saline–alkaline environment, the shear strength of rock joints and the production rate of CaCO₃ were higher, and the Sporosarcina pasteurii with domestication showed better joint repair performance. The peak shear strength of rock joints reinforced by MICP increased with curing time, with a quicker strength development in the early stage and a slower increase later on. The peak shear strength of cemented rock joints significantly surpassed that of uncemented rock joints. This research can provide valuable insights for the application of MICP technology in reinforcing rock joints in saline–alkaline environment.