Normal Stress-Dependent Frictional Weakening of Large Rock Avalanche Basal Facies: Implications for the Rock Avalanche Volume Effect

Y. F. Wang, J. J. Dong, Q. G. Cheng

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

To explore the mechanism behind the volume effect of rock avalanches observed in field data, a series of rotary shear tests were conducted at a shearing velocity of 0.87 m/s and varying normal stress levels (from 0.29 to 1.85 MPa) on soil collected from the basal facies of the Yigong rock avalanche in Tibet, China. This experimental study reveals that (1) as normal stress increases, the steady state apparent friction coefficient (μss) of the soil decreases, indicating a normal stress-dependent feature of μss; (2) the higher the normal stress, the lower the decay rate of μss; (3) water vaporization induced by frictional heating is commonly observed in the tests accompanied by large decreases in μss, and excess pore pressure is generated in the shearing zones of the samples due to vapor accumulation; and (4) with increases in normal stress and decreases in soil permeability, an increasing feature of excess pore pressure is reached. Based on the experimental results, we propose that the coupled effects of water vaporization induced by frictional heating in avalanche basal facies and depth-dependent permeability of avalanche basal facies should be contributed to the volume effect of rock avalanches.

Original languageEnglish
Pages (from-to)3270-3282
Number of pages13
JournalJournal of Geophysical Research: Solid Earth
Volume123
Issue number4
DOIs
StatePublished - Apr 2018

Keywords

  • avalanche dynamics
  • basal facies
  • normal stress
  • shearing behavior
  • volume effect
  • Yigong rock avalanche

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