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The role of frictional heating in the development of catastrophic landslides

The role of frictional heating in the development of catastrophic landslides
The role of frictional heating in the development of catastrophic landslides
In this work, a new thermo-mechanical model is developed by improving on an existing one, applicable to large deep seated landslides and rockslides consisting of a coherent mass sliding on a thin clayey layer. The considered time window is that of catastrophic acceleration, starting at incipient failure and ending a few seconds later, when the acquired displacement and velocity are such that the sliding material begins to break up into pieces. The model accounts for temperature rise in the slip zone due to the heat produced by friction, leading to thermoplastic collapse of the soil skeleton and subsequent increase of pore water pressure. This in turn drastically decreases the resistance to motion and allows the overlying mass to move downslope ever more freely.

The proposed model is implemented numerically and validated by back-analysing the two well-documented catastrophic landslide case histories of Vajont and Jiufengershan. The model is then employed to carry out a parametric study to systematically investigate the development of catastrophic failure in uniform slopes. It was found that the most influential parameters in promoting catastrophic collapse are (1) the static friction-softening rate a1, (2) the slope inclination ?, (3) the soil permeability kw, (4) the dynamic residual friction angle rd ? and (5) the overburden thickness H. The most dangerous situation is when a1, ? and H are very large and kw and rd ? are very low. Of the above, the ‘thermo-mechanical parameters’ kw and H deserve more attention as they have been introduced by the thermo-mechanical model and are not normally considered in standard stability analyses of uniform slopes. A second parametric study was performed to demonstrate that thermo-mechanical parameters alone can make a difference between a relatively non-catastrophic event and a catastrophic one. Hence, further insight into the design of landslide risk mitigation measures can be gained if, in addition to the standard site investigations, the permeability of the soil is measured and the depth of an existing or expected failure surface is measured or estimated respectively.
Cecinato, Francesco
45d87e7d-8021-4eca-9cb6-896a4e70276f
Cecinato, Francesco
45d87e7d-8021-4eca-9cb6-896a4e70276f
Zervos, Antonios
9e60164e-af2c-4776-af7d-dfc9a454c46e

Cecinato, Francesco (2009) The role of frictional heating in the development of catastrophic landslides. University of Southampton, School of Civil Engineering and the Environment, Doctoral Thesis, 240pp.

Record type: Thesis (Doctoral)

Abstract

In this work, a new thermo-mechanical model is developed by improving on an existing one, applicable to large deep seated landslides and rockslides consisting of a coherent mass sliding on a thin clayey layer. The considered time window is that of catastrophic acceleration, starting at incipient failure and ending a few seconds later, when the acquired displacement and velocity are such that the sliding material begins to break up into pieces. The model accounts for temperature rise in the slip zone due to the heat produced by friction, leading to thermoplastic collapse of the soil skeleton and subsequent increase of pore water pressure. This in turn drastically decreases the resistance to motion and allows the overlying mass to move downslope ever more freely.

The proposed model is implemented numerically and validated by back-analysing the two well-documented catastrophic landslide case histories of Vajont and Jiufengershan. The model is then employed to carry out a parametric study to systematically investigate the development of catastrophic failure in uniform slopes. It was found that the most influential parameters in promoting catastrophic collapse are (1) the static friction-softening rate a1, (2) the slope inclination ?, (3) the soil permeability kw, (4) the dynamic residual friction angle rd ? and (5) the overburden thickness H. The most dangerous situation is when a1, ? and H are very large and kw and rd ? are very low. Of the above, the ‘thermo-mechanical parameters’ kw and H deserve more attention as they have been introduced by the thermo-mechanical model and are not normally considered in standard stability analyses of uniform slopes. A second parametric study was performed to demonstrate that thermo-mechanical parameters alone can make a difference between a relatively non-catastrophic event and a catastrophic one. Hence, further insight into the design of landslide risk mitigation measures can be gained if, in addition to the standard site investigations, the permeability of the soil is measured and the depth of an existing or expected failure surface is measured or estimated respectively.

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More information

Published date: February 2009
Organisations: University of Southampton

Identifiers

Local EPrints ID: 72984
URI: https://eprints.soton.ac.uk/id/eprint/72984
PURE UUID: b7cd51a0-2549-450f-956e-20d9369f26c3
ORCID for Antonios Zervos: ORCID iD orcid.org/0000-0002-2662-9320

Catalogue record

Date deposited: 25 Feb 2010
Last modified: 06 Jun 2018 12:46

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