KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
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Mechanical Characteristics of Basalt in Jeju Island with Relation to Porosity

공극률에 따른 제주도 현무암의 역학적 특성

  • 문경태 (제주대학교 풍력특성화협동과정) ;
  • 박상렬 (제주대학교 토목공학과) ;
  • 김영찬 (한양종합건설주식회사) ;
  • 양순보 (한양종합건설주식회사)
  • Received : 2013.10.07
  • Accepted : 2014.05.31
  • Published : 2014.08.01
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Abstract

Volcanic rocks formed from magma near the earth surface commonly show vesicular structures due to exsolution of gaseous phases in magma. The distinction and the amount of vesicles are greatly various, but there are few researches on the effect of volume percentage of vesicles on the mechanical properties. In this study, mechanical characteristics of volcanic rocks in relation to the porosity are investigated through experimental tests with Jeju basalt. Two methods (the buoyancy method and the caliper method) are adopted for measuring porosity. And unconfined compressive strength, elastic modulus, tensile strength, and elastic wave velocity are plotted against porosity in order to propose the empirical relations after the regression analysis. Also, unconfined compressive strength and the elastic modulus in relation to the elastic wave velocity are proposed with the analysis. In the case of vesicular rocks with more than 5% porosity, it is found that the buoyancy method provides more accurate estimation of porosity than the caliper method. The unconfined compressive strength, the elastic modulus, and the elastic wave velocity decrease curvilinearly with increasing in porosity. Also, the unconfined compressive strength and the elastic modulus increase linearly with increasing in elastic wave velocity.

마그마에 의해 지표부근에서 형성된 화산암은 마그마 내부에 존재하던 휘발성분으로 인하여 기공이 많은 다공상 구조를 나타낸다. 이러한 기공은 다양한 크기와 양으로 분포되어 있으나 기공이 화산암의 역학적 특성에 어떠한 영향을 미치는지에 대한 연구는 매우 미비하다. 따라서 본 연구에서는 화산암 기공의 공극률에 따른 역학적 특성을 시험을 통해 확인하였는데, 화산암의 한 종류인 제주도 현무암에 있어 공극률을 두가지 측정방법에 따라 측정하고, 공극률과 일축압축강도, 탄성계수, 인장강도, 탄성파속도와의 관계 및 탄성파 속도와 일축압축강도, 탄성계수와의 관계를 회귀분석에 의해 추정하여 그 관계식을 제시하였다. 그 결과, 공극률 측정방법에 있어서는 공극률이 5%이상인 다공질 현무암의 경우 부력 이용 방법이 캘리퍼 방법보다 정확한 공극률을 예측한다고 판단되며, 공극률이 증가함에 따라 일축압축강도와 탄성계수, 탄성파 속도는 곡선적으로 감소하였고, 탄성파속도가 증가할수록 일축압축강도와 탄성계수는 선형적으로 증가하였다.

Keywords

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