Abstract: As a novel microbial reinforcement technology, microbially induced calcium carbonate precipitation (MICP) could change the hydraulic performance of fractured rock mass and barrier penetrations. Bacillus pasteurii was used as microbial filler to test the permeability performance of red sandstone specimens with penetrated fracture prepared by splitting. Furthermore, electrochemical impedance spectroscopy (EIS) method was employed to examine the influence of microbial filling on the structure of fractured rock mass, and further probe into the impermeability mechanism. Research results unveiled that 1) the permeability of fractured red sandstone can be reduced by 1-2 orders of magnitude by MICP; higher filling rate will result in better effect. 2) Crack width and confining pressure have impact on the change of permeability coefficient of fractured rock after microbial filling. 3) The permeability coefficient of fractured rock before and after microbial filling declines in a power relation with the growth of confining pressure. 4) The fractured sandstone after microbial filling is more conductive and denser than that before microbial filling, which explains the reduction of permeability coefficient.

Key words: fractured rock mass, impermeability mechanism, MICP, EIS, hydraulic performance