Development of Pentration Test Aparatus for Mountain Slope (IV) : A Measurement of Mechanical Impedance of Soil by Analyzing Stress Waves

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Other Title
  • 山地用貫入試験器の開発(IV) : 応力波形の解析による土の機械インピーダンスの測定
  • 山地用貫入試験機の開発-4-応力波形の解析による土の機械インピーダンスの測定
  • サンチヨウ カンニュウ シケンキ ノ カイハツ 4 オウリョク ハケイ ノ カ

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Description

In this report we developed the method for obtaining mechanical impedance of soil with high accuracy from the reflection coefficient α at the boundary between the lower end of rod and soil under the test. The results are summarized as follows: 1) Using the simplified penetrating apparatus and strain detecting system, measurements were carried out on the stress waves propagating and reflecting along the rod. 2) The mechanical impedance of soil is obtained from the reflection coefficient α. 3) For the purpose of selecting the best material for rod and hammer, measurements on mechanical impedance of Gum were carried out, which has a similar mechanical impedance with soil, with 4 kinds of rods; iron, aluminum alloy 5052, magnesium alloy AZ31, and PMMA (Plastics). With those material, the mechanical impedance of Gum is measured and the error was 51％ for iron rod, 12.9％ for PMMA rod and O.12％ for magnesium and aluminum alloy rods respectively. In case of using iron and PMMA rod, it is impossible to measure the impedance of soil with high accuracy since the mechanical impedance of iron is so high compared with the soil impedance and for PMMA rod due to it too much internal loss. 4) An alloy of magnesium(AZ31) is the best material for rod and hammer of the simplified penetrating test apparatus, since its internal loss is small and its mechanical impedance was larger than that of soil by one order.

Journal

  • 九州大学農学部演習林報告

    九州大学農学部演習林報告 54 85-103, 1984-03-26

    Research Institution of University Forests, Faculty of Agriculture, Kyushu University

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