Laser-induced fracturing technology in deep hard rock: Crack propagation patterns and development mechanisms

• The macro-meso-micro multi-scale damage response of sandstone after laser irradiation is clarified. • The three-dimensional spatial structure characteristics of sandstone crack network after laser irradiation are expounded. • The three-dimensional propagation law of sandstone cracks under laser irradiation is reproduced, and the driving mechanism of cracks is revealed. With the continuous increase of mining depth, the rock strength is rising, and the occurrence environment is becoming increasingly complex; the traditional rock breaking method is facing severe challenges. As an efficient rock breaking method with great engineering application potential, laser rock breaking can realize the rapid fracture and strength weakening of hard rock, significantly reduce the difficulty of hard rock excavation, and has the characteristics of low disturbance and no pollution, which opens a new path for the safe, green and efficient crushing and excavation of deep hard rock. To reveal the damage response and crack development mechanism of rock under the irradiation of laser, the laser-induced fracture sandstone experiment, micro test experiment and CT scanning experiment were carried out. Based on the ABAQUS simulation software, the laser-induced fracture sandstone simulation model considering damage development was established. The research clarified the multi-scale macro-fine and micro damage response of sandstone after laser irradiation, explored the three-dimensional spatial distribution characteristics of sandstone crack field after laser irradiation, revealed the driving mechanism of crack initiation and propagation of sandstone under laser action, and elaborated the spatial relationship between the crack field and the large principal stress field. The research results systematically understand the spatial distribution pattern, propagation pattern and driving mechanism of cracks under the irradiation of laser, and lay a theoretical foundation for the engineering application of laser rock breaking technology.