Microbially induced calcite precipitation (MICP) hasbeen widely applied for soil reinforcement

but its applications in rock mass permeabilityreduction have been rarely reported. To explore the plugging mechanism of rockjoints using MICP

artificial rock joint specimens made of transparent resinwere prepared

and laboratory MICP plugging experiments under six variousconditions considering MICP reaction influence factors were performed. Throughthe plugging experiments

evolution laws of rock joint transmissivity andhydraulic aperture

accompanied with corresponding CaCO distribution images

during plugging processes were obtained. The experimentalresults showed that the hydraulic aperture of rock joint approximatelydecreases linearly with grouting cycles during MICP plugging process

and thedecreasing rate is closely related to the CaCO distribution that issignificantly affected by grouting rate

injection time of fixation

bacterial

and reaction solutions

and standing time. Among the six experimentalconditions

both the plugging efficiency and effect are optimal under thefourth experimental condition

where the grouting rate is high and the groutingand standing time is the longest. After only two grouting cycles under the fourthexperimental condition

the rock jointtransmissivity decreases from 40.51×10 m/s to0.52×10 m/s with a decrease rate of 98.72%

and the hydraulic aperture decreases from 0.367mm to 0.086 mm with a decrease rate of 76.6%. Furthermore

the CaCO distribution on theupper and lower surfaces of rock joint specimens were observed

and CaCO in rock joints produced by MICP reaction was found to bring cementationstrength in a short time

which helps improve mechanical properties of rockjoints while reducing rock joint permeability.