Development of Directional Hydraulic Fracturing Technology Based on Guided Grooves and Its Application to Block Caving Mining

The natural caving method is an efficient and low-cost underground ore mining method. The premise of using the method is the presence of a certain number of developed fractures, which can induce continuous roof collapses in the undercutting process. To enable application of the natural caving method to intact ore bodies, a hydraulic fracturing control method based on guide grooves was proposed. By using the natural caving method, grooves with a certain depth are formed on borehole walls via hydraulic cutting, and hydraulic fracturing was carried out in the groove section to realize directional propagation of fractures, which meets the geological conditions required for natural caving mining. Under the engineering background of the Yanqianshan Iron Mine in Liaoning Province, China, a test stope for natural caving was designed in those intact ore bodies in the eastern mining area. This research validated the feasibility of the control technology through numerical computations based on guide grooves according to geological conditions and borehole size, and important technological parameters of hydraulic fracturing were designed. The hydraulic fracturing process was monitored through micro-seismic (MS) monitoring, thus determining the fracture propagation and evolution therein. The computational analysis and field monitoring show that the control technology based on guide grooves can achieve directional control of fracture propagation. The results indicate that the hydraulic fracturing control method based on guide grooves is feasible and applicable to artificial pre-treatment of fracture networks. Additionally, this research provides a new idea and technological prototype for the application of natural caving mining to intact ore bodies.