Experimental study on electricity resistivity of MICP-treated calcareous sand foundation

The heterogeneity is a technical problem for MICP-reinforced foundation. The electricity resistivity of a MICP-treated calcareous sand foundation is experimentally studied using the selft-developed multichannel measurement equipments. The effects of bacterial solution and cementation solution on the amplitude and variation law of electricity resistivity are investigated. The spatial differences of the MICP treatment effects in the calcareous foundation and the feasibility of using the electricity resistivity to monitor the MICP reaction process are discussed. The test results show that the electricity resistivity of the calcareous foundation is affected by the density, bacterial solution and cementation solution, among which the effects of cementation solution are the most significant. The electricity resistivity firstly increases, then decreases with the increase of MICP treatment times. The deeper soil has lower electricity resistivity than the upper soil. The electricity resistivity increases after the seventh or the eighth treatment. The reason for this phenomenon may be that the pores in the soil are gradually filled by the generated calcium carbonate after the repeated reinforcement, and the ion exchange channels in the soil are reduced, leading to an increase in the resistivity. The influences of calcium carbonate-filled pores on the resistivity are dominant at this time.