On the other hand, the surface of the sandpile is not able to resist large extrusion stress, which can be an additional criterion to describe the mechanics of sandpile avalanche.

• 另外，结果显示，沙堆表面也对崩塌也很敏感，表面不能承受很大的挤压（或者说张力），这个结果很类似液体的行为。