The axial decoupled charge is a key technology for controlling blasting energy, whose parameter settings directly affect rock fragmentation effect and project cost. However, existing research has predominantly focused on analyzing individual parameters in isolation, lacking systematic comparison of the coupled effects of multiple parameters such as the axial decoupled coefficient, decoupled medium type, and number of charge segments. To address this, six sets of axial decoupled charge structures with different parameters were designed, and blasting tests were conducted on large cylindrical granite samples (240 mm in diameter, 300 mm in height). Combined with numerical simulations and the generalized extreme value (GEV) distribution fitting, this study systematically investigates the influence mechanisms of the above parameters on blast pressure distribution, damage evolution, and fragment size distribution. The results indicate that the axial decoupled coefficient is the main factor controlling the fragmentation effect: the maximum fragment size and the distribution parameters \ (\) and \ (\) of the GEV distribution show an approximately linear increase with its value. Under the same decoupled coefficient, replacing air with water as the decoupled medium improves stress wave transmission efficiency due to its higher acoustic impedance, reducing the maximum fragment size by 7. 24% \ (\) 14. 07%. Employing the two-segment charge structure further reduces the maximum fragment size by 14. 67% \ (\) 21. 80% through spatial energy redistribution and stress wave superposition, leading to a more uniform fragmentation distribution. This study reveals the quantitative laws of rock fragmentation under the coupled influence of multiple parameters, providing experimental evidence and parameter optimization strategies for precision blasting design in engineering applications such as tunnel excavation and mining.
Fan et al. (Fri,) studied this question.