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1989 Fiscal Year Final Research Report Summary

Erosion of valley-floor bedrocks by sediment-laden flows

Research Project

Project/Area Number 63580194
Research Category

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

Allocation TypeSingle-year Grants
Research Field 自然地理学
Research InstitutionUniversity of Tsukuba

Principal Investigator

SUNAMURA Tsuguo  Inst. of Geosci., Univ. of Tsukuba, Prof., 地球科学系, 教授 (00011164)

Co-Investigator(Kenkyū-buntansha) MATSUKURA Yukinori  Inst. of Geosci., Univ. of Tsukuba, Assoc. Prof., 地球科学系, 助教授 (80107341)
Project Period (FY) 1988 – 1989
KeywordsSediment-laden flows / Erosion / Bedrocks / Fissures / Compressive strength / Artificial rocks
Research Abstract

(1) No quantitative studies on bedrock erosion due to sediment-laden flows have been conducted. In order to obtain a rudimentary knowledge on this subject a laboratory experiment on bedrock erosion by water flows without sediments was first performed using a recirculating flume. Artificial rocks made of a mixture of cement, sand, and water were used to simulate actual rocks in the field. In these simulated rocks having different strengths a slit was indented with various openings. To examine a flow in and around the slit, a visualization experiment was also conducted using neutral buoyant floats. When water flows into the interior of the slit, water particles hit the lower edge of the slit to act compressive force on the edge, so that this part is eroded more rapidly than the other part. The erosion is more vigorous as the opening of the slit becomes larger. The effect of opening tends to be more marked as the rock strength decreases. When erosion of the lower edge attains a certain critical value, water particles act no more compressive force on the edge. Difference in erosive force acting on the upper and lower edges becomes small, resulting in constancy of the relative height between the two edges.
(2) An experiment using a recirculating flume was performed to investigate bedrock erosion due to sediment-laden flows with a constant speed. Rock samples used here were collected from the field and had different strengths. The samples were subjected to shear force of the flows. The result showed that (1) the erosion occurs linearly with time, i.e., no temporal variation in erosion rate is present, and (2) the relationship between average erosion rate, R , and compressive strength of rocks, S_c , can be expressed by R = 0.17(4.3 - 1n S_c ) where the units of R and S_c are mm/hr and kg/cm^2, respectively.

  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] Tsuguo Sunamura: "A dynamical approach to wave-base problems" Transactions,Japanese Geomorphological Union. 11. 41-48 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tsuguo Sunamura,Yukinori Matsukura: "Bedroch erosion by sediment-laden flows" Transactions,Japanese Geomorphological Union.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 戸田真夏,砂村継夫: "人工岩石を用いた流水による岩盤侵食に関する実験的研究" 地形.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tsuguo Sunamura: "A dynamical approach to wave-base problems." Transactions, Japanese Geomorphological Union Vol. 11, pp. 41-48, 1990.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tsuguo Sunamura and Yukinori Matsukura: "Bedrock erosion by sediment-laden flows." Transactions, Japanese Geomorphological Union.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Manatsu Toda and Tsuguo Sunamura: "Experiments on erosion of artificial bedrocks by running water." Transactions, Japanese Geomorphological Union.

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-03-26  

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