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TitleFailure mechanism of an ancient sensitive clay landslide in eastern Canada
AuthorWang, B
SourceLandslides 2019 p. 1-13,
Alt SeriesNatural Resources Canada, Contribution Series 20180294
PublisherSpringer Science and Business Media LLC
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
AreaBreckenridge; Breckenridge Creek; Ottawa River
Lat/Long WENS -76.0000 -75.7500 45.5000 45.4167
Subjectssurficial geology/geomorphology; engineering geology; geophysics; landslides; landslide deposits; marine sediments; marine clays; sensitive clays; earthquakes; slope stability analyses; slope failures; models; surface waters; rivers; streams; shear tests; shear strength; boreholes; core samples; grain size distribution; plasticity; liquid limit analyses; pore pressures; Holocene; Recent; Champlain Sea Clay; Champlain Sea Sediments; Champlain Sea Plain; mitigation; Mitigation; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geoscientific sketch maps; tables; plots; profiles; cross-sections; models
ProgramPublic Safety Geoscience Assessing Earthquake Geohazards
Released2019 05 22
AbstractThis paper presents a geotechnical study of a Champlain Sea clay landslide at Breckenridge, Quebec, Canada. Previous studies have interpreted the landslide as triggered by an earthquake occurred about 1020 cal years BP. The current study is to estimate the minimum ground acceleration required to trigger the landslide as part of an effort to further understand the earthquake. The study consists of field and laboratory testing and slope stability analysis. Considerable evidences are presented to understand the slope failure mechanism. The result indicates a minimum horizontal ground acceleration of 0.28 g occurred at the site. Most importantly, the paper provides a case history for better understanding landslide hazards associated with sensitive clay failures in the region. Particularly, the study finds that the landslide is a 'flake' type failure as opposed to a retrogressive failure commonly perceived for Champlain Sea clay landslides. It brings to light the 'flake' slide as an important factor to consider for improvement of the current predictive models for sensitive clay failures. It also shows that earthquake-triggered 'flake' slide can be much larger than retrogressive failures in the same settings. The case history may therefore help as a reference for improved mitigative measures.
Summary(Plain Language Summary, not published)
This paper presents results of a geotechnical study of a Leda clay landslide in eastern Canada. The landslide was triggered by an earthquake about a thousand years ago. The study is to reconstruct the slope and to simulate the slope failure. Leda clay is known to be sensitive to disturbance. Once a failure starts in a small area, such as at a river bank, it may continue to fail progressively inland to a large distance - the so called retrogressive failure. This failure process has been the focus of sensitive clay landslide studies for decades. However, this study unveiled a different slope failure process. Numerous evidences indicate that a sensitive clay landslide can happen instantly over a distance that can be much greater than the typical retrogressive failures. This finding helped reconstruct the slope model. The estimated threshold ground acceleration is consistent with other observations. The results enhanced the knowledge about the region's landslide and earthquake hazards.

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