## 3 Results  
### Analysis of Concrete Block Fragmentation Results  
Due to the energy limitations of the pulse generation apparatus, a single electrical explosion was insufficient to fracture the concrete block. Consequently, multiple discharges were required to induce visible cracking. The number of discharges necessary varied among the different dielectric media tested, as follows: CO\({}_{2}\)-dissolved liquid (Figure 5g): four discharges were required to initiate visible cracking in the concrete block. All other seven dielectric media: three discharges were sufficient to induce visible cracking. In the aluminum powder suspension group (Figure 5a), the electrical explosion resulted in four uniformly expanding cracks in a cruciform pattern on the surface. The widest part of these cracks measured 0.5 cm, extending to one-third of the side walls, indicating that the shock wave acted uniformly around the borehole. In the iron powder suspension group experiment (Figure 5b), two main cracks and three minor cracks appeared on the surface. The main cracks extended to the outer edges of the sample but did not penetrate through. The widest part of the cracks reached 1.2 cm. This difference may be attributed to the characteristics of the iron powder suspension, which likely altered the propagation path and energy distribution of the shock wave generated by the electrical explosion within the rock. In the copper (II) oxide powder suspension group experiment (Figure 5c), we observed the development of three main cracks on the surface, with the widest part reaching 1 cm. One of these main cracks completely penetrated the rock sample, and at its outermost extent, a detachable rock fragment was formed. A significant amount of fragmented rock debris remained inside the borehole, with a small quantity of rock debris also appearing on the surface. Overall, its rock-breaking effect was second only to that of the iron (III) oxide powder suspension. In the iron (III) oxide powder suspension group experiment (Figure 5d), we found that the concrete block was completely penetrated, with cracks extending from the borehole to the outer edges of the concrete. The widest part of the cracks measured approximately 3 cm. Detached rock fragments reached diameters of up to 2 cm, indicating that this dielectric medium could generate stronger shock waves. In the potassium chloride solution group experiment (Figure 5e), we observed three distinct cracks forming a Y-shaped pattern on the surface. These cracks reached a maximum width of 0.7 cm. The main crack developed downward, penetrating the entire rock block while gradually decreasing in width. Partial rock debris appeared along the crack channels, and a notable fragmentation zone was evident at the borehole edge. These observations indicate that the shock waves generated by electrical explosions in potassium chloride solutions can produce a significant amount of rock fragmentation. In the sodium chloride solution group experiment (Figure 5f), the electrical explosion produced an X-shaped pattern on the surface, with four main cracks developing along the diagonals. The widest part of these cracks measured approximately 0.8 cm. The borehole edge remained smooth without a fragmentation zone, suggesting that in the sodium chloride solution, the shock waves primarily contributed to crack propagation rather than rock fragmentation. The  
Figure 5: Fragmentation effects of concrete blocks under electrical explosion in different dielectric environments: (**a**) aluminum powder suspension; (**b**) iron powder suspension; (**c**) copper (II) oxide powder suspension; (**d**) iron (III) oxide powder suspension; (**e**) potassium chloride solution; (**f**) sodium chloride solution; (**g**) CO\({}_{2}\)-dissolved liquid; (**h**) water. CO\({}_{2}\)-dissolved liquid group experiment (Figure 5g) required four electrical explosions before three fine cracks appeared in a Y-shaped distribution. This group demonstrated the poorest concrete fracturing effect in the entire experimental series.