EFFECTS OF WEATHERING ON STABILITY OF NATURAL SLOPES IN NORTH-CENTRAL KUMAMOTO

Through chemical process weathering, unwelded tuff pyroclastic flow deposits from Aso volcano have been altered to allophane and halloysite in geological time. As a result, natural slopes in areas abundant in weathered soils of unwelded tuff are prone to catastrophic failure in periods of heavy rainfall. Mineralogical, chemical and electron microscopy study of soil samples from unfailed slope and actual case of failed slopes have shown that the main clay mineral of these soils is halloysite. The results from strength tests have proved that the complex interaction between weathering and leaching processes transforms the soil grain structure into a collapsible structure considerably weak in a saturated state. The collapsible structure is identifiable from the low density in undisturbed state and hence, the low density criterion may be used as an indicator on the loss of strength that may result from field saturation during heavy rainfall. Besides, leaching accelerates internal erosion in the natural slopes, and hence risk of failure by the seepage forces. (A)

  • Availability:
  • Corporate Authors:

    Japanese Society of Soil Mech & Foundation Engrs

    Tokyo,   Japan 
  • Authors:
    • MSHANA, N S
    • Suzuki, A
    • KITAZONO, Y
  • Publication Date: 1993-12

Language

  • English

Media Info

  • Features: References;
  • Pagination: p. 74-87
  • Serial:
    • SOILS AND FOUNDATIONS
    • Volume: 33
    • Issue Number: 4
    • Publisher: JAPANESE GEOTECHNICAL SOCIETY
    • ISSN: 0038-0806

Subject/Index Terms

Filing Info

  • Accession Number: 00662343
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Jul 28 1994 12:00AM