## 1 Introduction  
Pre-splitting blasting is a technique that involves the creation of a pre-crack of a certain width between the excavation rock mass and the reserved rock mass before the detonation of the main blasting area; this is in order to mitigate the blasting vibration generated after the detonation of the main area and reduce the damage caused to the reserved rock mass, thereby ensuring the integrity of the slope [1]. In the practical application of pre-splitting blasting, the reasonable setting of pre-split hole parameters is particularly crucial; significant progress has been made in this field of research [2, 3]. [PERSON] et al. [4] used numerical simulation to investigate the effect of four different inter-hole delay times (0 us, 40 us, 80 us, and 120 us) and hole spacing on the effectiveness of pre-crack formation, and the optimal combination of a delay time of 80 us and a hole spacing of 60 cm was derived after field verification. [PERSON] et al. [5] analyzed the impact of the parameters of pre-splitting blasting on its effectiveness using numerical simulations and applied the findings to actual construction, achieving good results. [PERSON] et al. [6] explored the fracture characteristics of rock influenced by various joint angles via SHPB (Split Hopkinson Pressure Bar) experiments and numerical simulations, providing guidance for geotechnical engineering design. [PERSON] et al. [7] proposed a hole-by-hole pre-splitting blasting technique by conducting theoretical research and field experiments to compare the effects of hole-by-hole initiation pre-splitting blasting with conventional simultaneous pre-splitting blasting. The results showed that the average rate of reduction in the blasting vibration velocity for conventional same-row blasting was 26.40%, while that for hole-by-hole blasting was 41.45%. Based on numerical studies and theoretical analysis, [PERSON] et al. [8] provided an optimization scheme for pre-splitting blasting under high in situ stress conditions. [PERSON] et al. [9] proposed the axially decoupled spherical charge pre-splitting blasting (PSB-ADSC) technique and studied the smoothness of the fracture surface and the formation and development process of the pre-crack under PSB-ADSC conditions using high-speed photography and digital image correlation techniques on concrete models. The results indicate that the PSB-ADSC method can produce pre-cracks, fracture surfaces, and half-hole walls that are similar to those of traditional pre-splitting blasting. In open-pit mining, the damage to the reserved rock mass caused by blasting not only affects the economic efficiency of mine production but also directly relates to the safety of operations. The reasonable control of blasting-induced damage to the surrounding rock is crucial for ensuring the safety of mines and improving the efficiency of production [10]. Studies have shown that rock mass damage is closely related to changes in sound velocity, and blasting damage evolution models based on sound velocity changes have been established and applied [11; 12; 13]. [PERSON] et al. [14] proposed relationships between the damage variable D, crack density, and effective bulk modulus and effective Poisson's ratio, expanding the applicability of damage models. [PERSON] et al. [15] studied the surrounding rock damage induced by tunnel excavation in the Canadian Atomic Energy Underground Laboratory using ultrasonic tomography, based on the sensitivity of the ultrasonic velocity and amplitude to cracks. [PERSON] et al. [16] linked the development of cracks in materials to changes in the longitudinal wave velocity, using changes in the longitudinal wave velocity to evaluate the number of micro-cracks that developed in rock materials. [PERSON] [17] conducted several studies on the influence of various parameters, such as the structural plane conditions, depositional environment, and physical and mechanical properties of rock, on the blasting damage.