# Study on Dynamic Loading Characteristics of Rock Containing Holes
## 4 Simulation Results and Analysis
### Final Failure Modes  
Tables 5 and 6 show the displacement field and crack distribution diagrams for various specimens after undergoing uniaxial dynamic impact. In the displacement fields, different colors represent distinct levels of relative displacement, facilitating the visualization of movement within the specimen. Likewise, in the crack distribution diagrams, unique colors indicate the types of cracks present: green illustrates tensile cracks, and blue highlights shear cracks. The predominant cause of failure in the specimens was the advancement of edge cracks within the conical blocks situated at the ends of the specimens, reflecting the critical points of stress concentration and fracture initiation.  
The comparative analysis shown in Table 5, focusing on the failure modes of specimens with holes subjected to the same strain rate loading conditions, reveals that a larger hole diameter leads to an increased relative displacement of blocks at the specimen's incident face and a denser concentration of cracks surrounding the macro X-shaped main crack. This effect is likely due to the larger holes providing more room for the movement of conical blocks, which in turn promotes the formation of macro cracks.  
In the simulated impact experiments that were conducted, the occurrence of tensile and shear cracks was meticulously recorded across various failure modes in the specimens. To better visualize the variation in the number of cracks, the specimen with the smallest number of cracks under a strain rate of 100 s\({}^{-1}\) and with an 8 mm hole, which exhibited 2600 shear cracks, was chosen as a baseline for comparison. Figure 15 reveals that an increase in hole diameter is associated with a reduction in both tensile and shear crack numbers. This reduction is attributed to the holes facilitating the displacement of conical blocks, which in turn lessens microcrack generation. Consequently, this indicates that larger hole diameters encourage the formation of significant macroscopic cracks, altering the overall failure dynamics of the specimens.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Diameter of Hole**} & \multicolumn{2}{c}{**Strain Rate (100 s\({}^{-1}\))**} & \multicolumn{2}{c}{**Strain Rate (200 s\({}^{-1}\))**} \\ \cline{2-4}  & **Displacement Field** & **Crack Distribution** & **Displacement Field** & **Crack Distribution** \\ \hline
2 mm & 3000\(\pm\)300 & 3000\(\pm\)300 & 3000\(\pm\)300 & 3000\(\pm\)300 \\
4 mm & 3000\(\pm\)300 & 3000\(\pm\)300 & 3000\(\pm\)300 & 3  
In dynamic impact experiments, strain rate emerges as a crucial determinant of specimen mechanical behavior. Comparative analysis of displacement field diagrams at strain rates of 200 s\({}^{-1}\) and 100 s\({}^{-1}\) reveals that displacement at the conical blocks on the incident  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Diameter of Hole**} & \multicolumn{2}{c}{**Strain Rate (100 s\({}^{-1}\))**} & \multicolumn{2}{c}{**Strain Rate (200 s\({}^{-1}\))**} \\ \cline{2-3}  & **Displacement Field** & **C  
end is markedly greater under higher strain rate conditions, accompanied by pronounced block peeling at the specimen edges. As illustrated in Figure 16, high strain rates lead to a substantial increase in shear crack quantity, suggesting that specimen failure modes at elevated strain rates are predominantly governed by shear cracks, resulting in increased fragmentation.