## 3 Results
### Shockwave Energy Analysis
The electrohydraulic shock wave energy conversion efficiencies for copper (II) oxide and iron (III) oxide groups were 48.5% and 52.2%, respectively, far surpassing the 14.1% efficiency of the tap water group by factors of 3.4 and 3.7. This marked improvement in  
Figure 6: Strain waveforms of electrical explosions in different dielectric media. efficiency indicates that the ignition of micron-sized oxide powders during the electrical explosion process effectively intensifies the shock wave effect, enhances secondary shock wave energy, and significantly amplifies the contraction motion of concrete blocks, thereby improving rock-breaking efficiency. In the comparative analysis of the strain waveforms from the potassium chloride solution (Figure 6e) and sodium chloride solution (Figure 6f) groups with the tap water control group (Figure 6h), the impact of high electrical conductivity significantly influenced the shock wave characteristics, resulting in notable waveform differences. Within the primary shock wave period of the potassium chloride solution group, secondary shock waves arrived prematurely, manifesting on the descending edge of the primary shock wave. This phenomenon was also observed, albeit to a lesser extent, in the sodium chloride solution group. The expansive strain peak values for potassium chloride and sodium chloride solutions exceeded those of the tap water group by 10,350 \(\upmu\)e and 8911 \(\upmu\)e, respectively, corresponding to substantial increases of 31.9% and 27.5%. Concurrently, contraction peak strains were markedly reduced to 2154 \(\upmu\)e and 2474 \(\upmu\)e, representing decreases of 73.5% and 69.6%, respectively, compared to the tap water group. Calculations revealed shock wave energy conversion efficiencies of 51.5% and 41.6% for potassium chloride and sodium chloride solutions, respectively, surpassing the tap water dielectric by factors of 3.6 and 2.9. These results demonstrate the significant enhancement of shock wave energy by high-conductivity dielectric media, primarily manifested in increased shock wave expansion and restricted concrete block contraction. Furthermore, secondary shock waves propagated at higher velocities in high-conductivity dielectric media compared to other types, a characteristic conducive to the sustained expansion of concrete blocks, thereby improving electrical explosion rock-breaking efficiency. Comparative analysis of the strain waveforms from the CO\({}_{2}\)-dissolved liquid (Figure 6g) and the tap water control group (Figure 6h) revealed that the expansive strain peak value of the CO\({}_{2}\)-dissolved liquid exceeded that of the tap water group by only 2051 \(\upmu\)e, representing a modest increase of 6.3%. This slight enhancement reflects the limited promotion of shock wave expansion effects by the CO\({}_{2}\)-dissolved liquid. However, the concrete blocks exhibited more intense contraction with the CO\({}_{2}\)-dissolved liquid, with a prolonged duration of 0.25 ms. The contraction strain peak value surpassed that of the tap water group by 5108 \(\upmu\)e, corresponding to a substantial increase of 62.6%. This result demonstrates the significant effect of CO\({}_{2}\)-dissolved liquid in enhancing the contraction phase of concrete blocks. Notably, the shock wave energy conversion efficiency of the CO\({}_{2}\)-dissolved liquid was 13.6%, lower than that of the tap water group. This represents the only instance of decreased shock wave energy conversion efficiency observed in the study. Analysis suggests that the underlying mechanism for this phenomenon involves the release of dissolved CO\({}_{2}\) under high temperature and pressure conditions during the electrical explosion process. The resulting bubble pulsation enhanced shock wave propagation. However, following the primary shock wave action, the dissipation of bubbles and pressure reduction in the borehole led to the contraction of the concrete block under negative pressure rather than continued expansion.