Experimental Study on Mechanical and Permeability Characteristics of Reinforced Rock Based on the EICP Technology

Considering the influence of strongly weathered sandstone on engineering safety and stability during mine excavation, this study employs enzyme-induced calcium carbonate precipitation (EICP) technology for rock reinforcement. Through systematic experimentation involving conventional triaxial compression experiments and coupled seepage-stress analyses, we comprehensively investigate the evolution of strength parameters and deformation behavior in EICP-reinforced sandstone under varying stress levels. A permeability comparison under hydrostatic pressure and triaxial compression conditions further elucidates the stress-related hydraulic characteristics of original and reinforced rock. Key findings reveal that EICP reinforcement significantly enhances the mechanical performance of weathered sandstone, with great improvement in strength and deformation properties. However, subsequent analysis revealed that carbonate dissolution via seepage diminishes the long-term stabilization efficacy. Permeability evolution exhibits distinct phase characteristics: the permeability coefficient decreases gradually when the rock is subjected to increasing confining pressure, with the decreasing rate getting slower; and axial loading induces fundamentally different responses. Under increasing axial stress, the permeability coefficient of original samples decreases first and then increases, which is correlated with the deformation stage, whereas EICP-reinforced samples maintain continuous permeability reduction throughout loading cycles, which correlates strongly with its microstructural modifications. Further, EICP reinforcement alters the axial stress-permeability coupling mechanisms of the weathered sandstone.