The Grain-Size Distribution of Rock-Avalanche Deposits: Implications for Natural Dam Stability

摘要: The sedimentology of rock-avalanche deposits, mass movements that commonly cause natural dams is poorly understood. This paper presents the results detailed research into grain-size distribution and deposits. These data show sorted deposits composed angular, highly-fragmented clasts with preserved source stratigraphy. Grain-size distributions segregate based on rock type become finer distance travelled from when topographic constraints do not dominate. indicate inverse grading noted at often a misconception, main interior fragmentation variation only due to lithology. A facies model presented consisting surficial, coarse openwork carapace facies, fragmented body basal entrained substrate mixed debris. prove fractal in nature direct contrast Weibull previously cited for suggest confined comminution as formational mechanism. An application using finite element/limit equilibrium techniques simplified dam. modelling shows key failure sequence. idealised homogenous dam took 17.75 days fail; more sedimentologically realistic failed within 48 h lake reaches phreatic tonguing occurred.