Energy conversion and deposition behaviour in gravitational collapse of granular columns Energy conversion and deposition behaviour in gravitational collapse of granular columns

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Vol17 No.1: 216-229

Title】Energy conversion and deposition behaviour in gravitational collapse of granular columns

Author】HUANG Bo-lin1,2*; WANG Jian1,2; ZHANG Quan1,2; LUO Chao-lin3; CHEN Xiao-ting1,2

Addresses】1 Hubei Key Laboratory of Disaster Prevention and Mitigation, China Three Gorges University, Yichang 443002, China; 2 National Observatory of the Three Gorges Landslide, Yangtze River, Hubei Province, China Three Gorges University, Yichang 443002, China; 3 Pearl River Water Resources Research Institute, Pearl River Water Resources Research Institute, Guangzhou 510611, China

Corresponding author】HUANG Bo-lin

Citation】Huang BL, Wang J, Zhang Q, et al. (2020) Energy conversion and deposition behaviour in gravitational collapse of granular columns. Journal of Mountain Science 17(1). https://doi.org/10.1007/s11629-019-5602-9

DOI】https://doi.org/10.1007/s11629-019-5602-9

Abstract】The high-density gravitational collapse of granular columns is very similar to the movements of large collapsing columns in nature. Based on the development of dangerous columnar rock mass in fields, granular column collapse boundary condition in the physical experiments of this study is a new type of boundary conditions with a single free face and a three-dimensional deposit. Physical experiments have shown that the mobility of small particles during the collapse of granular columns was greater than that of large particles. For example, when particle size was increased from 5 to 15 mm, deposit runout was decreased by about 16.4%. When a column consisted of two particle types with different sizes, these particles could mix in the vicinity of layer interfaces and small particles might increase the mobility of large particles. In the process of collapse, potential and kinetic energy conversion rate is fluctuated. By increasing initial aspect ratio a, the ratio of the initial height of column to its length along flow direction, potential and kinetic energy conversion rate is decreased. For example, as a was increased from 0.5 to 4, the ratio of maximum kinetic energy obtained and total potential energy loss was decreased from 47.6% to 7.4%. After movement stopped, an almost trapezoidal body remained in the column and a fan-like or fan-shaped accumulation was formed on the periphery of column. Using multiple exponential functions of the aspect ratio a, the planar morphology of the collapse deposit of granular columns could be quantitatively characterized. The movement of pillar dangerous rock masses with collapse failure mode could be evaluated using this granular column experimental results.

Keywords】Granular columns; Rock collapse; Collapse experiments; Energy conversion; Deposit sequence; Deposit prediction