Formation mechanism of a rainfall triggered complex landslide in southwest China

Qiu xiang Huang, Xiang tao Xu, P. H.S.W. Kulatilake, Feng Lin

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

This case study is about a landslide that occurred after 4 days of heavy rainfall, in the morning of June 29, 2012, in Cengong County, Guizhou Province of China, geographical coordinated 108°20′-109°03′E, 27°09′-27°32′N, with an estimated volume of 3.3×106 m3. To fully investigate the landslide process and formation mechanism, detailed geotechnical and geophysical investigations were performed including borehole drilling, sampling, and laboratory tests coupled with monitoring of displacement. Also, a combined seepage-slope stability modeling was performed to study the behavior of the landslide. After the heavy rainfall event, the sliding process started in this area. The landslide development can be divided into different parts. The man-made fill area, spatially distributed in the south side of the landslide area with low elevations, slid first along the interface between the slope debris and the strongly weathered bedrock roughly in the EW direction. Consequently, due to severe lateral shear disturbance, the slope in the main sliding zone slid next towards the SW direction, along the sliding surface developed within the strongly weathered calcareous shale formation located at a depth of 25-35 m. This means it was a rainfall triggered deep-seated landslide. Finally, retrogressive failure of a number of upstream blocks occurred, which moved in more than one direction. The initial failure of the man-made fill area was the ‘engine’ of the whole instability framework. This artificial material with low permeability, piled up in the accumulation area of surface and sub-surface and destroyed the drainage capacity of the groundwater. The numerical modeling results agreed with the analysis results obtained from the laboratory and field investigations. A conceptual model is given to illustrate the formation mechanism and development process of the landslide.

Original languageEnglish (US)
Pages (from-to)1128-1142
Number of pages15
JournalJournal of Mountain Science
Volume17
Issue number5
DOIs
StatePublished - May 1 2020

Keywords

  • Complex landslide
  • Conceptual model
  • Lateral shear failure
  • Man-made fill
  • Shale formation

ASJC Scopus subject areas

  • Global and Planetary Change
  • Geography, Planning and Development
  • Geology
  • Earth-Surface Processes
  • Nature and Landscape Conservation

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