Akiba Yuri, Takashima Aika, Shima Hiroyuki
Department of Environmental Sciences, University of Yamanashi, 4-4-37, Takeda, Kofu, Yamanashi 400-8510, Japan.
Phys Rev E. 2021 Aug;104(2-2):025009. doi: 10.1103/PhysRevE.104.025009.
Outcrops of columnar joints made of solidified lava flows are often covered by semiordered polygonal cracks. The polygon diameters are fairly uniform at each outcrop, but their shapes largely vary in the number of sides and internal angles. Herein, we unveil that the statistical variation in the polygon shape follows an extreme value distribution class: the Gumbel distribution. The Gumbel law was found to hold for different columnar joints, regardless of the locality, lithologic composition, and typical diameter. A common distribution for columnar joints implies a universal class that may integrate the polygonal crack networks observed on the surface of various fractured brittle materials.
由固化熔岩流形成的柱状节理露头通常被半规则的多边形裂缝所覆盖。每个露头处多边形的直径相当均匀，但其形状在边数和内角数量上有很大差异。在此，我们揭示多边形形状的统计变化遵循一种极值分布类型：耿贝尔分布。研究发现，耿贝尔定律适用于不同的柱状节理，无论其位置、岩性组成和典型直径如何。柱状节理的共同分布意味着一个通用类别，它可能整合了在各种破裂脆性材料表面观察到的多边形裂缝网络。
