Enhancing Directional Rock Fracturing with Instantaneous Expanding Slit Former Technology

Traditional rock blasting with explosives is marked by extensive pulverization, chaotic fracturing, suboptimal shaping outcomes, and stringent controls. As a result, a nonexplosive technology for directional rock fracturing, named instantaneous expanding slit former (IESF), has been developed. This method employs specially designed perforated pipes for directional slicing, swiftly channeling expanding gases to form singular fractures in targeted directions within the rock. Through numerical simulation, this study contrasts the expansion traits and damage inflicted by traditional explosives [such as diazodinitrophenol (DDNP)] and IESF during directional rock fracturing. On-site directional blasting tests were employed to ascertain and verify the Riedel–Hiermaier–Thoma model parameters in this investigation. Utilizing the FEM, a three-dimensional model for directional blasting was developed, incorporating both DDNP and IESF. The numerical outcomes affirmed the relevance of fluid–solid coupling within the IESF model. An analysis encompassing the borehole’s upper, middle, and lower segments evidenced the efficiency of IESF technology for directional slicing. Drawing on these findings, field trials for roof cutting were executed in the Dongjiang coal mine, illustrating the method's efficacy for directional roof presplitting. IESF technology boasts significant advantages, including enhanced safety, a high rate of slit formation, and effective slit outcomes. The outcomes of this research offer crucial technical insights for deploying IESF in mining roof cutting operations.