Semantic segmentation model for remote sensing images based on U-Net++ guided by dual attention

Research on blasting craters is one of the most fundamental studies in blasting engineering. To elucidate the formation process and mechanisms of blasting craters and to investigate the roles of blasting stress waves and explosion gases in rock fragmentation during this process, a blasting load model was developed. This model is based on a double-exponential explosive load function and the equation of state for explosion gas pressure, incorporating the dynamic-static sequential effects of blasting. By combining the distinct loading characteristics of blasting stress waves and explosion gases, a discrete element numerical model of the blasting crater was established to simulate the development of fractures, rock fragmentation, and ejection of blasted rock. Simulations were performed both with and without the inclusion of explosion gas loading to explore the respective contributions of blasting stress waves and explosion gases to crater formation. The results show that the blasting crater dimensions simulated with the dynamic-static sequential loading model align closely with field test results, accurately capturing the formation and evolution of fractures in the blasting zone and the ejection behavior of fragmented rock. The high loading rate of blasting stress waves is the primary cause of ring-shaped microfractures in the near-field region of the explosion source, which can also induce reflective tensile damage, forming “slice drop” failure at free surfaces. Explosion gases, on the other hand, are the main drivers of radially extensive fractures in the far-field region of the explosion source and propel fragmented rock outward at a high velocity. Explosion gases exhibit not only quasi-static effects but also dynamic effects, extending the duration of blasting vibrations and amplifying the peak vibration velocity. The development of fractures during crater formation can be broadly categorized into three stages: stress wave-induced fracturing, explosion gas-induced fracturing, and deformation energy release-induced fracturing.