The influence of MICP treatment on the shear strength of granite residual soil and its effect on slope stability

To investigate the microbial induced cementation precipitation effects on the low vertical stress shear strength and slope stability of granitic residual soil, this study performed low-stress direct shear test to evaluate the shear strength of solidified granite residual soil under different concentrations of cementing solution, and its impact on the stability of granite residual soil slope was analyzed through numerical methods. The results demonstrate that the concentration of cementing fluid has a significant impact on the solidification effect, with the shear strength enhancement reaching its optimum at a concentration of 1.2 mol/L. Both cohesion and internal friction angle of the granitic residual soil specimens exhibited cubic polynomial relationships with increasing cementation solution concentration, where the cohesion enhancement served as the dominant factor governing shear strength eventually stabilizes as the concentration of the cementing solution increases.The slope stability factor demonstrates an initial rapid increase followed by a slower rise that eventually stabilizes as the concentration of the cementing solution increases. Compared with natural slopes, the stability of granite residual soil slopes after the curing of the cementing solution shows a lag in the time of decline, and the reduction is relatively small, which indicates the effectiveness of microbial curing.; Under the curing effect of a 1.2 mol/L cementing solution, the stability of granite residual soil slopes within a certain slope and soil thickness range can be effectively guaranteed. The research results provide theoretical support for the improvement of the shear resistance performance of residual granite soil and the design of slope protection projects.