Effect of microorganism on rock crack reinforcement under different treatment technologies

In recent years, the research of microbial induced calcium carbonate precipitation (MICP) technology in the field of rock fracture repair has become more and more in-depth, and is gradually applied to the practical engineering field. In order to deeply study the effects of different treatment conditions and different cement concentrations on the effect of rock crack reinforcement by MICP technology, two different processes of peristaltic pump grouting and immersion grouting were used to carry out indoor tests on rock cracks, and determine the optimal process of rock crack reinforcement by microorganisms. Based on the above test results, the optimal treatment process parameters were obtained. On this basis, the test of rock crack reinforcement by microbial immersion grouting under different cement solution concentrations (0.5 mol/L, 0.7 mol/L and 1.0 mol/L) was carried out, and the quantitative analysis of the influence of cement solution concentration on the reinforcement effect was carried out. The results show that under the same cement concentration, the interfacial shear strength of rock cracks strengthened by peristaltic pump grouting process is about 0.28 kPa, the interfacial shear strength of rock cracks strengthened by immersion grouting process is about 0.89 kPa, and the interfacial shear strength of rock samples strengthened by immersion grouting is about 3.2 times that of rock samples repaired by peristaltic pump grouting. Under the condition of immersion grouting, the concentration of cement solution has a significant effect on the interfacial shear strength of reinforced rock samples. The ratio of interface cohesion between reinforced fracture and unreinforced rock sample increases linearly with the increase of cement solution concentration. For different shapes of rock samples, the results show that the growth rate of fracture interface cohesion of cylinder rock samples is significantly higher than that of cuboid rock samples.