Abstract: Microbial induced calcium carbonate precipitation (MICP) is an environmentally friendly and promising technique for ground improvement. However, the treating process is closely related to the infiltration characteristics of the slurry Therefore, a monitoring method applying electrical resistivity tomography (ERT) technique to MICP slurry infiltration process is proposed. MICP treatment was performed on the quartz sand by one-step mixed-grouting method. ERT monitoring and conductivity analysis were performed during the process. The three-dimensional resistivity variation of sand samples was obtained. After the treatment, the distribution of calcium carbonate content was determined. The results indicates that: (1) The electrical resistivity increased when the urea generally hydrolyzed during the MICP reaction. (2) The distribution of low electrical resistivity area was mainly dominated by the diffusion and mixing process of the grouting fluid. (3) During the MICP treatment, carbonate precipitation and infiltration of grouting fluid interacted, jointly affecting the reinforcement effect. (4) The resistivity spatiotemporal evolution can be effectively traced by ERT, which could accurately reflect the infiltration of treating suspension and then evaluate the reinforcement effect. This experiment demonstrates the permeability of ERT applying on MICP reinforcing, provides new ideas and research direction on MICP application. 

Key words: Microbial induced calcium carbonate precipitation MICP, electrical resistivity tomography ERT, infiltration process, soil
resistivity