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

Gespeichert in:

Bibliographische Detailangaben
Zeitschriftentitel:	Journal of Geophysical Research: Solid Earth
Personen und Körperschaften:	Wang, Y. F., Dong, J. J., Cheng, Q. G.
In:	Journal of Geophysical Research: Solid Earth, 123, 2018, 4, S. 3270-3282
Format:	E-Article
Sprache:	Englisch
veröffentlicht:	American Geophysical Union (AGU)
Schlagwörter:	Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Geochemistry and Petrology Geophysics

Details
Zusammenfassung:	<jats:title>Abstract</jats:title><jats:p>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 (<jats:italic>μ</jats:italic><jats:sub>ss</jats:sub>) of the soil decreases, indicating a normal stress‐dependent feature of <jats:italic>μ</jats:italic><jats:sub>ss</jats:sub>; (2) the higher the normal stress, the lower the decay rate of <jats:italic>μ</jats:italic><jats:sub>ss</jats:sub>; (3) water vaporization induced by frictional heating is commonly observed in the tests accompanied by large decreases in <jats:italic>μ</jats:italic><jats:sub>ss</jats:sub>, 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.</jats:p>
Umfang:	3270-3282
ISSN:	2169-9313 2169-9356
DOI:	10.1002/2018jb015602