###### Abstract  
In order to optimize the parameters of a pre-splitting blasting hole network, taking an open-pit mine in Inner Mongolia as the engineering background, the numerical models of different pore sizes and hole spacing were established by LS-DYNA software. The stress wave propagation law, peak stress change and rock fracture state under various working conditions were analyzed. The optimization formula of a hole network relationship was proposed and verified on site. The results show that the shock wave generated by the explosion propagates rapidly upward from the explosion source and forms a plastic flow zone around the two boreholes. The energy consumption is the largest at this stage. With the propagation of the stress wave, energy dissipates, and its waveform gradually attenuates to a compression wave and seismic wave. In each working condition, a 110 mm aperture first cracked in the stress wave superposition area compared with other working conditions, while a 120 mm aperture delayed evolution to the seismic wave compared with different borehole aperture, and the energy attenuation rate is the slowest. Meanwhile, the fastest energy attenuation rate is with the 130 mm borehole aperture. With the attenuation of the propagation energy of the stress wave, among the four measuring points set at the center of the connection between the two boreholes, the Y-direction stress of the observation points B, C and D is stable between 2.3 and 3.5 MPa, and the Y-direction stress of the observation point A is strenuous between \(-\)1.3 and 1.2 MPa. The B, C and D observation points of 90-130 mm aperture conditions showed rock cracking at 7-9 times, 7-9 times, 7-10 times, 7-11 times, and 7-11 times hole spacing, respectively. The cracks of the two boreholes were interconnected. The optimal hole network relationship is obtained by fitting: y = 1.12 + 0.076x, where y is the optimal hole diameter and hole spacing multiple, and x is the hole diameter, which is verified by engineering. After blasting, the slope is smooth and smooth, and the half-hole rate is guaranteed to be above 90%. pre-splitting blasting; hole network parameters; stress wave propagation; peak stress; field verification +
Footnote †: journal: Applied  
factors. Unreasonable hole network parameters will lead to excessive destruction of rock mass or not form pre-cracking, which not only cannot achieve the preset effect but also wastes manpower and material resources, and it even causes safety risks [5; 6]. To solve this problem, domestic and foreign scholars have conducted a lot of research on blasting parameters. [PERSON] et al. [7] selected controllable blasting design parameters affecting peak particle velocity (PPV) for ground vibration assessment. Two prominent statistical tools, principal component analysis (PCA) and stepwise selection and elimination (SSE), were used to identify the key controllable parameters affecting PPV. Multiple linear regression (MLR) technology was used to determine the correlation coefficients between 44 field test blasting design parameters and PPV. [PERSON] et al. [8] take into account the action time of the explosion pulse generated by the gas outflow of the detonation product, and they derive the relationship between the reasonable drilling and blasting parameters that minimize the drilling cost under the same rock crushing quality. [PERSON] et al. [9] studied the west slope of an open-pit coal mine in Buzhaoba and optimized the pre-splitting blasting parameters; they also analyzed the blasting effect and optimal blasting parameters under different blasting parameters in fragile rock mass. [PERSON] et al. [10] used the geological conditions of Nanliang Mine and proposed a method of pre-splitting blasting residual coal pillars. The influence mechanism of pre-splitting blasting on residual coal pillars was analyzed by combining theoretical analysis with numerical simulation, and the reasonable blasting parameters were determined.