Preliminary investigations of rheological properties of busan clays and possible implications for debris flow modelling

Sueng Won Jeong, Sang Nam Yoon, Sung Sik Park, Gil Young Kim, Seong Pil Kim, Jang Jun Bahk, Nyeon Keon Kang, Sang Hoon Lee, Sung Gyo Chung

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

3 Scopus citations

Abstract

To investigate the post-failure dynamics of subaerial and subaqueous landslides in various environments, we need a detailed analysis of the geotechnical and rheological behaviour of fine-grained sediments. For fine-grained sediments found in the subaerial and subaqueous environments, rheological research should be conducted as a prelude to understanding flow behaviour and hazard assessment. In this paper, the rheological characteristics of Busan clays from the Nakdong deltaic plain are examined in a shear rate-controlled system. A comparison is made between the Busan clays and low-activity clays in terms of rheometer geometry. Flow curves obtained from the controlled shear rate and the shear stress mode are examined. The viscosity and yield stresses obtained from different geometries, which may produce wall-slip among cylinder, ball-measuring and vane-measuring systems, are highlighted. Based on the relationship between the liquidity index and rheological values (viscosity and yield stress), flow motions are compared. Results show that the differences in mobility are significant when assuming that the flowing materials behave as a Bingham fluid. The runout distance is controlled by the yield stress of fine-grained sediments. Differences in yield stress may be caused by wall roughness and the distance between the ball (vane) and the wall in the rheometer. Under the same geomorphological conditions, the runout distance calculated from vane-measuring systems is much lower than that from ball-measuring and cylinderic systems. These difficulties must be minimized to predict debris flow mobility and to correctly perform hazard risk assessment.

Original languageEnglish
Title of host publicationAdvances in Natural and Technological Hazards Research
PublisherSpringer Netherlands
Pages45-54
Number of pages10
DOIs
StatePublished - 2014

Publication series

NameAdvances in Natural and Technological Hazards Research
Volume37
ISSN (Print)1878-9897
ISSN (Electronic)2213-6959

Keywords

  • Ball-measuring and vane-measuring rheometer
  • Busan clays
  • Debris flow mobility
  • Rheological properties

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