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Prediction of Failure Risk Level based on Weakness caused by Weathering and Evaluation of Resistance for Erosion on Shirasu Slope

Research Project

Project/Area Number 04452228
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 基礎・土質工学
Research InstitutionKYUSHU UNIVERSITY

Principal Investigator

OCHIAI Hidetoshi  Kyushu Univ., Civil Eng. (Suiko), Professor, 工学部, 教授 (00039679)

Co-Investigator(Kenkyū-buntansha) UMEZAKI Takeo  Kyushu Univ., Civil Eng., Research Associate, 工学部, 助手 (50193933)
OTANI Jun  Kyushu Univ., Civil Eng., Associate Professor, 工学部, 助教授 (30203821)
HAYASHI Shigenori  Kyushu Univ., Civil Eng. (Suiko), Associate Professor, 工学部, 助教授 (80112308)
Project Period (FY) 1992 – 1993
Project Status Completed (Fiscal Year 1993)
Budget Amount *help
¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥5,300,000 (Direct Cost: ¥5,300,000)
KeywordsShirasu / Weathering / Repetition of wetting and drying / Slope disaster / Multiple logistic model / Solid particles / Solidification / Surface erosion / せん断特性 / 破壊 / 多重ロジステイックモデル / 単純せん断試験 / サクション / 模型実験
Research Abstract

Shirasu widely distributed in southern Kyushu in Japan is weak in the resistance for water so that erosion failure and surface slide failure on natural slopes have occured repeatedly. It is very important for making up a counterplan of preventing disasters to evaluate the transition of basic factors of failure caused by the weathering and erosion actions. In this study, the time transition of resistance force for weathering and erosion on Shirasu slopes is evaluated by the laboratory tests and field tests, and the method predicting risk level of slope failure is proposed based on their results. The main conclusions are summarized as follows :
1) The influence of repetition of wetting and drying on the shear properties of Shirasu appears in the deformation property. namely, the failure formula as a rock materials changes into that as a soil material.
2) Shirasu in the equilibrium under applied shear stress larger than residual shear strength at saturation collapse when taking the action of wetting.
3) Shirasu constituted by only soil particles with small value of density, however, is weak in water flow, Shirasu mixing the soil particles with different densities is hard to erode until the coarse particles with high value of density start flowing out.
4) After cutting off in-sifu Shirasu slope, the resistance force for soil hardness tester of Yamanaka type decreases with time passing.
5) The properties of undisturbd Shirasu can be estimated from weathering erosion properties of artificially solidified Shirasu.
6) The occurrence of slope disaster can be dividd into three groups ; basic factor of failure, motive factor and expansion-restrain factor. Disaster prevention potential can be evalated from the multiple logistic analysis based on the consideration that these factors are regarded as risk factor.

Report

(3 results)
  • 1993 Annual Research Report   Final Research Report Summary
  • 1992 Annual Research Report
  • Research Products

    (11 results)

All Other

All Publications (11 results)

  • [Publications] 梅村 順 落合 英俊 林 重徳: "表面流によるしらすの侵食特性" 九州大学工学集報. 64. 553-540 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 梅村 順 落合 英俊 林 重徳: "乾湿の繰返しによるしらすの風化特性に関する実験的研究" 火山灰に関する研究討論会論文集. 19-24 (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 梅村 順 林 重徳 落合 英俊: "地すべりを対象とした防災ポテンシャルの評価" 土木学会論文集. 487/III-26. 11-20 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Jun UMEMURA, Hidetoshi OCHIAI and Shigenori HAYASHI: "Eerosive Property of Volcanic Pumiceous Ash Soil 'Shirasu' Caused by Surface Flow" Technology Reports of Kyushu Univ.Vol. 64. 533-540 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Jun UMEMURA, Hidetoshi OCHIAI and Shigenori HAYASHI: "Experimental Study on The Alteration of Physical and Mechanical Properties of "SHIRASU" by Weathering Due to Repeated Dry and Wet Conditions" Proceedings of The Volcanic Ash Soils Symposium. 19-24 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Jun UMEMURA Hidetoshi OCHIAI and Shigenori HAYASHI: "Evaluation of The Prevention Potential Against Landslide" Proceedings of JSCE. 487/III-26. 11-20 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 梅村順,落合英俊,林重徳: "表面流によるしらすの浸食特性" 九州大学工学集報. 64. 553-540 (1991)

    • Related Report
      1993 Annual Research Report
  • [Publications] 梅村順,落合英俊,林重徳: "乾湿の繰返しによるしらすの風化特性に関する実験的研究" 火山灰に関する研究討論会論文集. 19-24 (1992)

    • Related Report
      1993 Annual Research Report
  • [Publications] 梅村順,落合英俊,林重徳: "地すべり災害を対象とした防災ポテンシャルの評価" 土木学会論文集. 487 III-26. 1-10 (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] 梅村 順・落合 英俊・林 重徳: "乾湿の繰返しによるしらすの風化特性に関する実験的研究" 火山灰に関する研究討論会論文集. 19-24 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 梅村 順・落合 英俊・林 重徳: "表面流によるしらすの侵食特性" 九州大学工学集報. 64. 533-540 (1991)

    • Related Report
      1992 Annual Research Report

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Published: 1992-04-01   Modified: 2016-04-21  

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