## 1 Introduction
[19] specifically studied the crack propagation mechanism of rock as an example material under different loading rates. [PERSON] et al. [20] specifically focused their research on actual coal mining and revealed the damage development process of this material using acoustic methods based on the spatial aggregation characteristics of cracks. They achieved good prediction and experimental fitting results. [PERSON] et al. [21] used a software simulation combined with physical experiments and found that compared to other fractured rock masses, the defect roadway with a single root crack and an inclination angle of 45\({}^{\circ}\) has the lowest static and dynamic stability. [PERSON] [22] also established a fractal damage  
Figure 1: Schematic diagram of rock mass blasting with cracks. joint model based on the fractal damage theory, studied the transmission and reflection of stress waves between joints, and derived the analytical expression of the transmission and reflection coefficient of stress waves across joints from the fractal damage joint model. In [PERSON]'s study [23], a general Green's function solution of elastic wave propagation due to rock blasting was analytically derived. Navier's equations of motion were assumed as governing equations, and a general two-dimensional elastodynamic Green's function was obtained in terms of displacement. The strain and stress fields related to the displacement of Green's function were also obtained using the theory of elasticity. In 2021, [PERSON] et al. [24] conducted a numerical study on the dynamic behavior of stress waves in cracks, indicating that Rayleigh waves have a significant impact on the propagation and variation of cracks in all directions. The above research is based on practical engineering experiments; due to the short overall time, it is difficult to analyze the propagation of waves after explosions based on the stress wave theory, and the influencing factors cannot be explored by changing a single variable in the same situation. However, based on numerical model calculation research, although models containing existing cracks were set up for research, there is no in-depth and regular research on the different states of crack existence. The field to which this type of problem belongs is almost blank and quite valuable because the brittle characteristics of rock materials can cause the original cracks to rapidly expand and connect under high loading rates such as explosive loads, and even generate huge cracks. The repeated loading of conventional explosive stress waves will cause cracks to continuously expand in a very short period, even leading to hazards such as rock bursts, slope instability, and tunnel collapse. In recent years, some studies have found that interconnected cracks have a significant impact on the dynamic response of deep engineering projects such as tunnels under blasting stress waves. The stress distribution around tunnels changes significantly due to the presence of cracks, leading to the initiation and propagation of new cracks. More importantly, one study found that the dynamic crack propagation behavior is influenced by the direction of blasting stress wave incidence [25]. The main objective of this study is to confirm the feasibility of the stress wave theory for predicting the location of the dangerous area around the gun hole under dynamic load. In this paper, the dynamic propagation behavior of new cracks and existing cracks in a single crack model with different angles around the blasting hole is studied. This study focuses on stress waves as the main research object, but it is evident that the network structure formed by cracks has a significant guiding effect on the propagation of stress waves. Therefore, to eliminate the influence of fragmented regions on the propagation direction, in simulation, the model at the same angle is simulated twice, with the same peak load applied.