Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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A Study of Locally Changing Pore Characteristics and Hydraulic Anisotropy due to Bedding of Porous Sandstone

다공질 사암의 층리에 따른 국부적 공극특성 변화와 수리 이방성 특성

  • 양화영 (과학기술연합대학원 대학교 지반신공간공학부) ;
  • 김한나 (서울대학교 공과대학 에너지시스템공학부) ;
  • 김경민 (과학기술연합대학원 대학교 지반신공간공학부) ;
  • 김광염 (한국건설기술연구원 SOC성능연구소 Geo인프라연구실) ;
  • 민기복 (서울대학교 에너지자원공학과)
  • Received : 2013.06.10
  • Accepted : 2013.06.27
  • Published : 2013.06.30
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Abstract

Anisotropy observed in sedimentary rock such as sandstone is mainly caused by existence of bedding consequently influencing on its hydraulic characteristics. The aim of this study is to investigate the influence of locally changing pore structure due to bedding on the hydraulic anisotropy of sandstone, in terms of localized porosity. X-ray CT scan is applied to observe the internal pore structures which is hard to be seen by other experimental methods. Permeability test is also conducted for samples cored at every $15^{\circ}$ from $0^{\circ}$ to $90^{\circ}$ with respect to bedding plane. As a result, the permeability anisotropy is manifest having 1.8 of anisotropy ratio ($k_{90^{\circ}}/k_{0^{\circ}}$) and corresponds with the anisotropy of porosity due to bedding.

퇴적암에서 나타나는 이방성은 층리에 의한 영향이 크며, 암석의 수리적 특성에도 영향을 주게 된다. 본 연구에서는 층리가 발달한 다공질 사암을 대상으로, 층리구조에 의해 발생한 공극구조 이방성이 사암의 수리 이방성에 미치는 영향을 분석하였다. 사암의 공극구조 이방성 파악을 위해 X-ray CT(computed tomography)를 이용하여 내부 공극률의 변화양상을 분석하였다. 층리방향에 따른 수리이방성은 층리면과 수평면이 이루는 각도를 $0^{\circ}$에서 $90^{\circ}$까지 $15^{\circ}$간격으로 코어링한 샘플을 제작하여 투수실험을 통해 파악하였다. 투수실험 결과 층리면과 투수방향이 수직인 경우 투수율이 가장 작은 값을 나타낸 반면, 층리면과 투수방향이 평행일 때 가장 높은 투수율을 나타내었으며, 평균 수리이등방비($k_{90^{\circ}}/k_{0^{\circ}}$)가 1.8로 층리에 따른 수리 이방성이 확연하게 나타났다. 또한, 이러한 사암의 수리이방특성은 층리에 의해 공극특성이 서로 다른 층상구조가 형성되기 때문임을 확인하였다.

Keywords

References

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