• Title/Summary/Keyword: 이중 비틀림 시험

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Influence of the Geometry of Guide Groove on Stress Corrosion Index of Rock in Double Torsion Test (이중 비틀림 시험에서 유도 홈의 형상이 암석의 응력부식지수에 미치는 영향)

  • 정해식;미원우삼;전석원
    • Tunnel and Underground Space
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    • v.14 no.5
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    • pp.363-372
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    • 2004
  • Double torsion (DT) tests were carried out to investigate the influence of the geometry of guide groove on stress corrosion index of Kumamoto andesite. The fracture toughness was measured in the constant displacement rate, which was set to 2.07 MN/m$^{3}$2/ in average regardless of crack velocity. Stress corrosion indices, n were evaluated using specimens with rectangular, circular and triangular grooves and were 37, 36 and 38 in average, respectively. The n values were constant regardless of the groove geometry, however the DT specimen with triangular groove geometry showed the largest standard deviation in the relationship between crack velocity and stress intensity factor. The DT test was found to be effective in using a rectangular-grooved specimen and the width of the groove must be greater than the average grain size of minerals.