# Study on the Influence of Rock Shape on Rolling Distance
## 3 Analysis of Experimental Results
### Relationship between Rock Shape and Rolling Distance
In the cases of test blocks D, E, and F, their rolling process involves a substantial ground contact area, resulting in significant axis transition and increased post-transition rolling resistance compared to initial rolling resistance. Consequently, in the absence of collisions, they tend to roll about the axis with lower rolling resistance, consistent with the findings of [PERSON] [48]. Certain test blocks that undergo offset exhibit varying degrees of reduced rolling distances. In addition to the potential for test block A to undergo a change in rolling axis during offset, which could elevate rolling resistance, the remaining test blocks experience kinetic energy loss due to offset. This occurs because, during the offset process, an angle exists between the direction of rolling kinetic energy and the direction of motion, as depicted in Figure 14. This impedes the complete utilization of the test block's kinetic energy, leading to a decrease in its rolling distance. Figure 12: \(RF\) for different-shaped test blocks. Figure 13: Variation of \(\delta\) during axis transition of the test block. If the offset angle remains constant, the influence of rotational inertia causes the angle between the rolling kinetic energy direction and motion direction to vanish upon offset completion, as illustrated in Figure 15a. When the offset angle continuously varies, the angle between the rolling kinetic energy direction and motion direction oscillates between \(0^{\circ}\) and the current offset angle during each occurrence, as depicted in Figure 15b. Figure 16 illustrates the stopping positions of test blocks A, B, and E as they roll on rolling surfaces made of different materials with an initial velocity of 2.2 m/s, and as their velocities reach zero. Figure 14: Variation of the angle between the direction of rolling and rolling kinetic energy before and after offset. Figure 11:0 Variation of \(\delta\) during axis transition of the test block: (**a**) the offset angle no longer changes; (**b**) the offset angle is constantly changing. The results indicate that, on flat ground, the primary determinant of rolling distance is the test block shape, whereas the hardness of the ground material has a comparatively limited effect. Observation of rolling characteristics during the test blocks' transition between two distinct materials reveals that varying material hardness leads to uneven deformation of the rolling surface during the transition. During the transition from a highly deforming surface to a less deforming one, the test block encounters a \"step\" created by the deformation difference between the two materials. The height of this \"step\" is determined by the hardness contrast between the two adjacent materials, as depicted in Figure 11:1 The presence of the \"step\" influences the test block rolling distance. A relatively low \"step\" is less likely to hinder the test block during rolling, resulting in minimal disruption. However, a \"step\" of a certain height can lead to collisions with the test block, diminishing its rolling distance or even causing it to cease rolling immediately post-collision. In instances where adjacent materials exhibit similar hardness at the boundary, the obstruction at the boundary is lower in height and has a minimal impact on the test block rolling.