三軸圧縮試験における庵治花崗岩のひずみ挙動および変形特性に対する封圧と間隙水圧の効果  [in Japanese] Effects of Confining Pressure and Pore Water Pressure on the Strain Behavior and Deformation Property of Aji Granite under Triaxial Compression Test  [in Japanese]

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Author(s)

    • 澤山 和貴 Sawayama Kazuki
    • 広島大学理学部地球惑星システム学科|現所属:九州大学大学院工学府地球資源システム工学専攻 Department of Earth and Planetary Systems Science, Faculty of Science, Hiroshima University|Present address: Department of Earth Resources Engineering, Graduate School of Engineering, Kyushu University
    • 片山 郁夫 Katayama Ikuo
    • 広島大学大学院理学研究科地球惑星システム学専攻 Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University

Abstract

<p>庵治花崗岩の三軸圧縮試験を封圧10-40MPa,間隙水圧10-30MPa,ひずみ速度5.0×10<sup>-6</sup> s<sup>-1</sup>の条件下で行い,ひずみゲージで測定した変形中のひずみを解析した.最大軸差応力およびダイラタンシー開始応力は有効圧の上昇に伴い増加し,水の存在下ではやや減少する傾向が確認された.ヤング率は有効圧の上昇とともに若干増加し,水の存在下ではやや低い値を示すが,ポアソン比には有効圧や水による変化はみられなかった.試料中のマイクロクラックに起因するダイラタンシーは,乾燥状態の試験では封圧が低いほど促進されるが,間隙水圧下の試験では有効圧が低いほど抑制される傾向が確認された.この傾向は,間隙水が試料内部の応力集中を緩和させる働きがある可能性を示している.また,いずれの間隙水圧下の試験でも,最大軸差応力の約96%の応力を越えると試料への注入水体積が急増する傾向が確認され,このしきい値を境に試料内の空隙の連結が促進されることが示唆された.</p>

<p>To investigate the effects of confining pressure and pore water pressure on the strain behavior and deformation properties of Aji granite, triaxial compression tests were performed at a constant strain rate (5.0×10<sup>-6</sup> s<sup>-1</sup>) under confining and pore water pressures of 10-40 MPa and 10-30 MPa, respectively. During the tests, axial and radial strains were measured by two biaxial strain gauges. The results revealed increases in maximum differential stress and onset of dilatancy with effective confining pressure. Young's modulus tended to increase with confining pressure and decrease with pore water pressure. However, Poisson's ratio remained nearly constant under these experimental conditions. Dilatancy is related to the formation of micro-cracks during deformation and is enhanced at low confining pressures under dry conditions. In contrast, it tends to be suppressed at a high pore water pressure (low effective confining pressure) under wet conditions. These results indicate that stress concentration at the crack tip can be relaxed by the presence of pore water. Moreover, water injection into the specimen during wet experiments rapidly increases at a stress level of ~96% maximum differential stress. This rapid increase can be attributed to the formation of a micro-crack network.</p>

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 122(11), 603-615, 2016

    The Geological Society of Japan

Codes

  • NII Article ID (NAID)
    130005240924
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • ISSN
    0016-7630
  • NDL Article ID
    027780503
  • NDL Call No.
    Z15-174
  • Data Source
    NDL  J-STAGE 
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