## 2 Experimental Introduction
### Experimental Procedure
#### 2.5.1 Influence of Block Shape on Rolling Speed  
As evident from Figures 12-14, under identical conditions, spherical block A exhibits a significantly higher rolling speed compared to blocks B and E. Analysis suggests that the rolling resistance experienced by spherical block A during rolling depends on the roughness of the rolling slope. In contrast, blocks B and E primarily experience rolling resistance based on their contact with the rolling surface, specifically the contact area between the block and the surface after each roll. Blocks B and E have much larger contact areas with the slope during rolling compared to block A, substantially increasing the rolling resistance torque they need to overcome. From the perspective of energy consumption, for blocks with the same mass, the larger the rolling resistance torque, the more work that is required for each roll, leading to a greater energy consumption. Hence, for blocks rolling on a hard slope surface, their shape is the primary factor leading to their energy consumption. From Figure 14, it can be observed that on a 60 degree slope, for blocks E (roundness of 0.9) and G (roundness of 0.97) with equal mass, released from a height of 90 cm, the actual speeds are 2.71 m/s and 3.08 m/s, respectively. Block E's speed is 13.65% lower than that of block G, and this phenomenon is consistently observed in experiments with blocks of different shapes. This indicates that the rolling speed of the blocks is somewhat related to the two-dimensional cross-sectional roundness of their rolling surface and is positively correlated with the roundness perpendicular to the rolling surface. The fundamental reason for this phenomenon is that, for blocks with the same volume, sections with  
Figure 14: Block rolling speed on 60\({}^{\circ}\) slope. Figure 13: Block rolling speed on 45\({}^{\circ}\) slope. higher roundness have a smaller contact area with the slope during rolling compared to sections with lower roundness. Consequently, blocks with higher roundness experience less resistance to overcome, resulting in faster rolling speeds. During the test, it was found that when the test block rolled downwards from the slope, it tended to roll around the rolling axis with the least rolling resistance. This aligns with the conclusion drawn by [PERSON] (2018) through the analysis of field rockfall test data. A parameter called the length-to-width ratio (\(\lambda\)) was defined, where \(\lambda=l_{min}/l_{max}\), with \(l_{max}\) being the maximum length of the block and \(l_{min}\) being the minimum length. Analysis of the experimental data revealed that when \(\lambda<0.33\), the blocks typically roll around the axis with minimum rolling resistance and rarely change their rolling axis, as shown in Figure 15. The lateral offset of the test block in the rolling process is small, attributed to the low rolling resistance of the test block itself and the slope surface. This enables the test block to maintain a consistent rolling direction. When \(1>\lambda>0.33\), the test block usually undergoes a transformation of the rolling axis during the rolling process, as illustrated in Figure 16. The frequency of rolling axis transformations correlates positively with the magnitude of \(\lambda\). For test block E, its rolling resistance is relatively high, and the difference in rolling resistance between any two-dimensional sections is not significant. Consequently, during the rolling process, the rolling axis easily undergoes transformations, leading to an increased energy loss and a reduction in the rolling speed of the test block.