Abstract: Rock instability is a common geological hazard in human activities, engineering construction, and natural environments. Its widespread and frequent occurrence highlights the urgent need for effective prevention. Both academic and engineering communities generally agree that fracture is a dominant factor controlling rock stability, and healing of shallow fractures with small aperture to prevent further expansion is an effective and economical strategy for actively prevention of rock instability hazards. This study focuses on studying the non-penetrating steep rock fractures with small aperture, and adopts microbialinduced calcium carbonate precipitation (MICP) as the bio-healing technique. A MICP based bio-healing method for nonpenetrating steep rock fractures with high bridging rate was proposed based on an innovative three-step injection strategy. The feasibility of the method was systematically examined through a series of laboratory bio-healing tests, spatiotemporal evolution characteristic tracking of the bio-healing process, testing of physical and mechanical properties, and analysis of typical local microstructures. The regulation laws of key factors affecting the bio-healing effect were identified, the microstructural evolution characteristics and the optimal combination scheme of influencing factors for each treatment step was determined.

Key words: MICP, rock fractures, bio-healing, non-penetrating, bridging rate