Preliminary study on the shear strength of rough rock joint reinforced by Microbially induced calcite precipitation method

Microbially Induced Calcite Precipitation (MICP) has emerged as an ecologically friendly geotechnical technology widely applied for soil reinforcement. However, few researches on rock joint reinforcement by using the MICP method have been reported. In this study, artificial rock joint specimens with the morphology characteristics of the tenth Barton’s standard profile were prepared by using cement slurry rock-like material. Both MICP and cement slurry grouting methods were used to reinforce the artificial rock joint specimens, and direct shear tests under three levels of normal stress were performed to investigate the shear strength behaviours. The results reveal that both the peak and residual shear strength of MICP-treated rock joint increase with the specimen curing time as a result of the increasing bonding strength of the calcium carbonate layer generated during the MICP process, and the MICP method is more effective than the cement slurry grouting method to enhance the shear strength of rock joint. However, both the shear failure of both MICP-treated and cement-slurry-treated rock joint firstly occurs along the interface between rock surface and the infill layer, and then the asperities are involved to form a mixture contact of rock-infill and rock-rock during the subsequent shear process.